Alternative wrist and elbow joint proprioception reconstruction methods based on neurostimulation systems

Abstract

The present invention discloses a replacement wrist and elbow joint proprioception reconstruction method based on a neural electrical stimulation system, comprising the following steps: 1) the user attaches an electrical stimulation module to the upper arm and wears a prosthesis; an angle sensor is placed inside the prosthesis; 2) the angle sensor monitors the user's limb movement posture information and transmits it to a microcontroller; 3) the microcontroller generates an electrical stimulation pattern according to the movement posture information or electrical stimulation parameter information; 4) the microcontroller controls the electrical stimulation module to generate electrical stimulation acting on the user according to the electrical stimulation pattern, and transmits the electrical stimulation pattern to a mobile terminal for display through a data transmission module. The present invention utilizes the superficial skin sensation pattern of the amputee's residual limb, combines the user's proprioception with the prosthesis movement state, and makes the induced replacement sensation closer to the natural sensation.

Description

Technical Field

[0001] The present invention relates to the field of electrical stimulation, and in particular to a replacement wrist and elbow joint proprioception reconstruction method based on a neural electrical stimulation system. Background Art

[0002] Amputees face a series of inconveniences in life due to the loss of limbs. Artificial prosthetic technology aims to provide amputees with a similar experience to real human hands by simulating the appearance or function of real human hands. Cosmetic prostheses with simulated appearance only provide amputees with the experience of complete limb appearance, while functional prostheses with the purpose of providing normal human hand functions control the activities of prostheses by collecting input signals to achieve different functions.

[0003] In domestic and foreign research, upper limb prosthetic technologies with multiple degrees of freedom have emerged, which can control the movements of fingers, wrists, elbows and other parts, including flexion and extension of fingers, flexion and extension and rotation of wrist joints, and flexion and extension and rotation of elbow joints. However, research and application in the field of prosthetic sensory feedback needs to be deepened.

[0004] There are now prosthetic limbs that can provide feedback to users through proprioception reconstruction. Traditional proprioception rehabilitation technology mainly uses the body's own proprioceptive receptors or tablets to perform muscle strength tasks to study the recovery of bionic proprioception functions, or collects electromyographic signal encoding to control prosthetic movement, while using somatosensory evoked potentials to stimulate users to produce proprioceptive feedback. However, the following problems still exist:

[0005] 1) Currently, most laboratories use invasive interventions that require implanting a neuromuscular-electrode interface device into the residual limb of an amputee to stimulate the sensory nerve fibers of the residual limb in order to restore the limb sensation of the amputee. However, the implantation of the device will cause certain damage to the body of the amputee.

[0006] 2) Currently, there is no proprioceptive feedback reconstruction technology for prosthetic wrist and elbow joints. Most prosthetic limbs use vibration stimulation to complete motion information feedback, which can achieve 3-DOF motion patterns, such as finger extension and flexion, arm pronation and supination, and wrist extension and flexion. The commercial prosthetic hand VINCENT evolution 2 uses mechanical vibration stimulation to provide tactile feedback to users. However, there is no prosthetic limb that can achieve proprioceptive feedback based on movement to provide a richer and more sophisticated sensory control experience.

[0007] 3) The current encoding method for proprioception reconstruction is only applicable to amputees with phantom limb sensation. However, only about 1 / 3 of amputees retain phantom limb sensation, and the phantom limb sensation cannot completely correspond to each part of the upper limb, which also makes this method only applicable to some amputees with phantom limb sensation. This limits the scope of application of this technology to a certain extent. Summary of the invention

[0008] The purpose of the present invention is to provide an alternative wrist and elbow joint proprioception reconstruction method based on a neural electrical stimulation system, which is intended to provide amputees with feedback of the motor sensory information of the wrist or elbow joint of the prosthesis. The neural electrical stimulation system includes an electrical stimulation module, an angle sensor, a data transmission module, a microcontroller and a mobile terminal.

[0009] The alternative wrist and elbow proprioception reconstruction method includes the following steps:

[0010] 1) The user wears the prosthesis and places stimulation electrodes on the skin surface of the upper arm stump. The portable electrical stimulation module connected to the stimulation electrodes is installed in the receiving cavity of the prosthesis; an angle sensor is placed inside the prosthesis;

[0011] 2) The angle sensor monitors the motion posture information of the prosthesis controlled by the user and transmits it to the microcontroller;

[0012] 3) The microcontroller generates an electrical stimulation pattern according to the motion posture information, and the electrical stimulation pattern refers to the setting of electrical stimulation parameters; among the electrical stimulation parameters, the electrical stimulation pulse width, the electrical stimulation frequency and the electrical stimulation amplitude need to be determined according to the sensory function of the specific user, and the electrical stimulation amplitude is a constant, and the specific value is between 0 and 8 mA, which should be higher than the electrical stimulation sensory threshold and lower than the pain threshold, and the specific value is affected by the sensory sensitivity level of the disabled subject's residual limb.

[0013] The electrical stimulation mode includes the electrical stimulation channel number, electrical stimulation timing, electrical stimulation amplitude, electrical stimulation pulse width, and electrical stimulation frequency; the electrical stimulation parameter information is transmitted from the mobile terminal to the microcontroller through the data transmission module; the electrical stimulation timing includes the order in which the electrical stimulation channel generates stimulation signals;

[0014] The electrical stimulation parameter information can also be set by the user in the mobile terminal, and personalized adjustments can be made according to the individual differences of different users, and transmitted to the microcontroller by the mobile terminal through the data transmission module;

[0015] 4) The microcontroller controls the electrical stimulation module to generate electrical stimulation for the user according to the electrical stimulation pattern, and transmits the electrical stimulation pattern to the mobile terminal for display through the data transmission module;

[0016] Further, the electrical stimulation module includes n electrical stimulation generation circuits and ring electrodes; n is a natural number;

[0017] The ring electrode includes n channels, which are respectively denoted as CH1, CH2, ..., CHn; one channel of the ring electrode is connected to an electrical stimulation generating circuit;

[0018] The electrical stimulation generating circuit comprises a unipolar to bipolar conversion circuit and a voltage-controlled constant current source circuit;

[0019] The unipolar-to-bipolar circuit converts the received single-phase constant current pulse signal into a bipolar constant current pulse signal.

[0020] The voltage-controlled constant current source circuit is then used to isolate the influence of human body impedance on the current signal, and transmit the electrical stimulation signal to the ring electrode, so that the ring electrode performs electrical stimulation on the user.

[0021] Furthermore, the two-phase constant pulse current signal is a two-phase current pulse signal that is negative first and then positive.

[0022] Furthermore, the movement posture information includes wrist flexion, wrist extension, wrist pronation, wrist supination, elbow flexion, and elbow extension.

[0023] Furthermore, the determining factors of the electrical stimulation channel number and the electrical stimulation intensity parameters include the wrist joint flexion and extension movement angle, the wrist joint rotation angle, and the elbow joint flexion and extension movement angle.

[0024] Furthermore, the annular electrode includes 8 channels, which are respectively denoted as CH1, CH2, ..., CH8.

[0025] Furthermore, when the prosthesis is in a straight state, the direction perpendicular to the palm is the positive direction of the Y axis, the middle axis of the upper arm is the Z axis, the direction pointing to the fingertips is the positive direction of the Z axis, the direction perpendicular to both the Y and Z axes is the X axis, and the direction perpendicular to the thumb is the positive direction of the X axis. The angle θ1 of the prosthetic wrist flexion and extension is defined as: the angle of the palm surface controlled by the prosthetic wrist flexion and extension motor in the plane where the X axis is located, which deviates from the Z axis. Flexion is positive and extension is negative.

[0026] When the motion posture information is a wrist straight state (θ1 = 0°), the selected electrical stimulation channel numbers include channel CH1 and channel CH5; channel CH1 and channel CH5 output electrical stimulation at the same time;

[0027] When the motion posture information is in the wrist flexion state, when the angle θ1 is between 0° and 30°, the selected electrical stimulation channel numbers include channel CH2 and channel CH4, and channel CH2 and channel CH4 output electrical stimulation simultaneously;

[0028] When the movement posture information is in the wrist flexion state, when the angle θ1 is between 31° and 60°, the selected electrical stimulation channel number includes channel CH3;

[0029] When the motion posture information is in the wrist extension state and the angle θ1 is between 0° and -30°, the selected electrical stimulation channel numbers include channel CH6 and channel CH8, and channel CH6 and channel CH8 output electrical stimulation simultaneously;

[0030] When the movement posture information is the wrist extension state and the angle θ1 is between -31° and -60°, the selected electrical stimulation channel number includes channel CH7.

[0031] Furthermore, when the prosthesis is in a straight state, the direction perpendicular to the palm outward is the positive direction of the Y axis, the middle axis of the upper arm is the Z axis, the direction pointing to the fingertips is the positive direction of the Z axis, the direction perpendicular to both the Y and Z axes is the X axis, the direction perpendicular to the thumb is the positive direction of the X axis, the forward rotation of the thumb is pronation, and the backward rotation of the thumb is supination. The angle θ2 of the prosthetic wrist rotation is defined as: the angle between the vector perpendicular to the palm outward when the prosthesis rotates around the middle axis of the forearm (Z axis) and the y axis;

[0032] When the wrist joint is in a straight state (θ2 = 0°), the selected electrical stimulation channel numbers include channel CH1;

[0033] When the wrist joint performs pronation, the selected electrical stimulation channel numbers include channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5; channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5 output electrical stimulation in sequence;

[0034] When the wrist joint performs supination movement, the selected electrical stimulation channel numbers include channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5; channel CH5, channel CH4, channel CH3, channel CH2, and channel CH1 output electrical stimulation in sequence.

[0035] Further, the elbow straight state is defined as: when the axis of the forearm and the axis of the upper arm are on the same straight line; the angle θ3 of the prosthetic elbow flexion and extension is defined as: the angle between the axis of the forearm and the axis of the upper arm;

[0036] When the movement posture information is the elbow straight state (θ3 = 0°), the selected electrical stimulation channel number includes channel CH7;

[0037] When the movement posture information is elbow flexion and the angle θ3 is between 0° and 45°, the selected electrical stimulation channel numbers include channel CH6 and channel CH8, and channel CH6 and channel CH8 output electrical stimulation simultaneously;

[0038] When the movement posture information is elbow flexion and the angle θ3 is between 46° and 90°, the selected electrical stimulation channel numbers include channel CH1 and channel CH5, and channel CH1 and channel CH5 output electrical stimulation simultaneously;

[0039] When the movement posture information is elbow flexion and the angle θ3 is between 91° and 135°, the selected electrical stimulation channel numbers include channel CH2 and channel CH4, and channel CH2 and channel CH4 output electrical stimulation simultaneously;

[0040] When the movement posture information is elbow extension and the angle θ3 is between 0° and 45°, the selected electrical stimulation channel numbers include channel CH8 and channel CH6, and channel CH8 and channel CH6 output electrical stimulation simultaneously;

[0041] When the movement posture information is elbow extension and the angle θ3 is between 46° and 90°, the selected electrical stimulation channel numbers include channel CH5 and channel CH1, and channel CH5 and channel CH1 output electrical stimulation simultaneously;

[0042] When the movement posture information is elbow extension and the angle θ3 is between 91° and 135°, the selected electrical stimulation channel numbers include channel CH4 and channel CH2, and channel CH4 and channel CH2 output electrical stimulation simultaneously.

[0043] The technical effects of the present invention are undoubted, and the present invention has the following effects:

[0044] 1) The present invention uses a transcutaneous electrical nerve stimulation method to induce sensation, which can reduce damage to experimental subjects compared with implanted stimulation methods.

[0045] 2) The present invention utilizes the superficial sensory pattern of the skin of the amputee's residual limb and uses the position of the stimulation electrode to encode the movement state of the prosthesis, so that the induced replacement sensation is closer to the natural sensation.

[0046] 3) The target population of the present invention is prosthetic users without phantom limb sensation. Compared with the methods based on induced finger sensation and bionic coding, the present invention expands the applicable population of prosthetic sensory reconstruction technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of a neural electrical stimulation system for controlling the motion angle of a prosthetic wrist and elbow joint according to the present invention;

[0048] Figure 2 This is a hardware structure diagram of the neural electrical stimulation system of the present invention;

[0049] Figure 3 For the positioning of the ring electrode on the upper arm stump;

[0050] Figure 4 It is a schematic diagram of the angle between the wrist joint space rectangular coordinate system and the axis where the forearm and upper arm are located. Figure 4 (a) is the left-handed rectangular coordinate system, Figure 4 (b) is the right-handed rectangular coordinate system, Figure 4 (c) the angle between the axes of the forearm and upper arm;

[0051] Figure 5 This is a schematic diagram of the movement pattern of the wrist and elbow joint; Figure 5 (a) is a schematic diagram of wrist extension and wrist flexion; Figure 5 (b) is a schematic diagram of wrist pronation and supination; Figure 5 (c) is a schematic diagram of elbow flexion and extension;

[0052] Figure 6 is the wrist joint angle coding scheme;

[0053] Figure 7 Coding scheme for elbow joint angle;

[0054] Figure 8 This is the waveform of the electrical stimulation pulse. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0056] Embodiment 1:

[0057] See also Figures 1 to 7 , a replacement wrist and elbow joint proprioception reconstruction method based on a neural electrical stimulation system, wherein the neural electrical stimulation system includes an electrical stimulation module, an angle sensor, a data transmission module, a microcontroller and a mobile terminal;

[0058] The alternative wrist and elbow proprioception reconstruction method includes the following steps:

[0059] 1) The user attaches the discharge stimulation module to the upper arm and wears the prosthesis; an angle sensor is placed inside the prosthesis;

[0060] 2) The angle sensor monitors the user's limb movement posture information and transmits it to the microcontroller;

[0061] 3) The microcontroller generates an electrical stimulation pattern according to the motion posture information or the electrical stimulation parameter information;

[0062] The electrical stimulation mode includes the electrical stimulation channel number, electrical stimulation timing, electrical stimulation amplitude, electrical stimulation pulse width, and electrical stimulation frequency; the electrical stimulation timing includes the order in which the electrical stimulation channels generate stimulation signals; among the electrical stimulation parameters, the electrical stimulation pulse width and the electrical stimulation frequency are determined according to the sensory function of the specific user, and the electrical stimulation amplitude is a constant, and the specific value is maintained between 0 and 8 mA, which should be higher than the user's electrical stimulation sensation threshold and lower than the pain threshold. The specific value is affected by the sensory sensitivity level of the disabled subject's residual limb.

[0063] The electrical stimulation parameter information can also be set by the user in the mobile terminal, and personalized adjustments can be made according to the individual differences of different users, and transmitted to the microcontroller by the mobile terminal through the data transmission module;

[0064] 4) The microcontroller controls the electrical stimulation module to generate electrical stimulation for the user according to the electrical stimulation pattern, and transmits the electrical stimulation pattern to the mobile terminal for display via the data transmission module.

[0065] The electrical stimulation module includes n electrical stimulation generation circuits and ring electrodes; n is a natural number;

[0066] The ring electrode includes n channels, which are respectively denoted as CH1, CH2, ..., CHn; one channel of the ring electrode is connected to an electrical stimulation generating circuit;

[0067] The ring electrode includes n channels, which are respectively denoted as CH1, CH2, ..., CHn; one channel of the ring electrode is connected to an electrical stimulation generating circuit;

[0068] The electrical stimulation generating circuit comprises a unipolar to bipolar conversion circuit and a voltage-controlled constant current source circuit;

[0069] The unipolar-to-bipolar circuit converts the received single-phase constant current pulse signal into a bipolar constant pulse current signal;

[0070] The voltage-controlled constant current source circuit is then used to isolate the influence of human body impedance on the current signal, and transmit the electrical stimulation signal to the ring electrode, so that the ring electrode performs electrical stimulation on the user.

[0071] The biphasic constant pulse current signal is a biphasic current pulse signal which is first negative and then positive.

[0072] The movement posture information includes wrist flexion, wrist extension, wrist pronation, wrist supination, elbow flexion, and elbow extension.

[0073] The determining factors of the electrical stimulation channel number and the electrical stimulation intensity parameters include the wrist joint flexion and extension movement angle, the wrist joint rotation angle, and the elbow joint flexion and extension movement angle.

[0074] The annular electrode includes 8 channels, which are respectively denoted as CH1, CH2, ..., CH8.

[0075] When the prosthesis is in a straight state, the direction perpendicular to the palm is the positive direction of the Y axis, the middle axis of the upper arm is the Z axis, the direction pointing to the fingertips is the positive direction of the Z axis, the direction perpendicular to both the Y and Z axes is the X axis, and the direction perpendicular to the thumb is the positive direction of the X axis. A spatial rectangular coordinate system is established, and the angle θ1 of the prosthetic wrist flexion and extension is defined as: the angle of the palm surface controlled by the prosthetic wrist flexion and extension motor in the plane where the X axis is located, which deviates from the Z axis. Flexion is positive, and extension is negative.

[0076] When the motion posture information is a wrist straight state (θ1 = 0°), the selected electrical stimulation channel numbers include channel CH1 and channel CH5; channel CH1 and channel CH5 output electrical stimulation at the same time;

[0077] When the motion posture information is in the wrist flexion state, when the angle θ1 is between 0° and 30°, the selected electrical stimulation channel numbers include channel CH2 and channel CH4, and channel CH2 and channel CH4 output electrical stimulation simultaneously;

[0078] When the movement posture information is in the wrist flexion state, when the angle θ1 is between 31° and 60°, the selected electrical stimulation channel number includes channel CH3;

[0079] When the motion posture information is in the wrist extension state and the angle θ1 is between 0° and -30°, the selected electrical stimulation channel numbers include channel CH6 and channel CH8, and channel CH6 and channel CH8 output electrical stimulation simultaneously;

[0080] When the movement posture information is the wrist extension state and the angle θ1 is between -31° and -60°, the selected electrical stimulation channel number includes channel CH7.

[0081] Furthermore, when the prosthesis is in a straight state, the direction perpendicular to the palm outward is the positive direction of the Y axis, the middle axis of the upper arm is the Z axis, the direction pointing to the fingertips is the positive direction of the Z axis, the direction perpendicular to both the Y and Z axes is the X axis, and the direction perpendicular to the thumb is the positive direction of the X axis. A spatial rectangular coordinate system is established. The forward rotation of the thumb is called pronation, and the backward rotation of the thumb is called supination. The angle θ2 of the prosthetic wrist rotation is defined as: the angle between the perpendicular palm outward vector and the y axis when the prosthesis rotates around the middle axis of the forearm (Z axis);

[0082] When the wrist joint is in a neutral position, the selected electrical stimulation channel numbers include channel CH1;

[0083] When the wrist joint performs pronation, the selected electrical stimulation channel numbers include channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5; channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5 output electrical stimulation in sequence;

[0084] When the wrist joint performs supination movement, the selected electrical stimulation channel numbers include channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5; channel CH5, channel CH4, channel CH3, channel CH2, and channel CH1 output electrical stimulation in sequence.

[0085] The elbow straight state is defined as: when the axis of the forearm and the axis of the upper arm are on the same straight line; the angle θ3 of the prosthetic elbow flexion and extension is defined as: the angle between the axis of the forearm and the axis of the upper arm;

[0086] When the movement posture information is the elbow straight state (θ3 = 0°), the selected electrical stimulation channel number includes channel CH7;

[0087] When the movement posture information is elbow flexion and the angle is between 0° and 45°, the selected electrical stimulation channel numbers include channel CH6 and channel CH8, and channel CH6 and channel CH8 output electrical stimulation simultaneously;

[0088] When the movement posture information is elbow flexion and the angle is between 46° and 90°, the selected electrical stimulation channel numbers include channel CH1 and channel CH5, and channel CH1 and channel CH5 output electrical stimulation at the same time;

[0089] When the movement posture information is elbow flexion and the angle is between 91° and 135°, the selected electrical stimulation channel numbers include channel CH2 and channel CH4, and channel CH2 and channel CH4 output electrical stimulation at the same time;

[0090] When the movement posture information is elbow extension and the angle is between 0° and 45°, the selected electrical stimulation channel numbers include channel CH8 and channel CH6, and channel CH8 and channel CH6 output electrical stimulation at the same time;

[0091] When the movement posture information is elbow extension and the angle is between 46° and 90°, the selected electrical stimulation channel numbers include channel CH5 and channel CH1, and channel CH5 and channel CH1 output electrical stimulation simultaneously;

[0092] When the movement posture information is elbow extension and the angle is between 91° and 135°, the selected electrical stimulation channel numbers include channel CH4 and channel CH2, and channel CH4 and channel CH2 output electrical stimulation simultaneously.

[0093] Embodiment 2:

[0094] See also Figures 1 to 7 , a replacement wrist and elbow proprioception reconstruction method is applied to a neural electrical stimulation system for controlling the motion angle of a prosthetic wrist and elbow joint, the system comprising an angle sensor module, a microcontroller, a multi-channel electrical stimulation module and a WIFI module (WIFI-1, WIFI-2). The multi-channel electrical stimulation module comprises an electrical stimulation generation circuit and a ring array of stimulation electrodes.

[0095] The angle sensor module includes angle sensors 1, 2 and angle sensor 3, which are respectively placed at the wrist joint and the elbow joint, and are used to obtain the two-way motion posture information of the wrist joint and the elbow joint of the prosthesis in real time and send it to the microprocessor.

[0096] The microcontroller reads the motion posture information of the prosthesis, converts the motion posture information into a corresponding electrical stimulation pattern according to the alternative wrist and elbow joint proprioception reconstruction method, and distributes it to the corresponding electrical stimulation module 3.

[0097] The electrical stimulation mode includes: selection of electrical stimulation channel number, electrical stimulation timing, electrical stimulation amplitude, electrical stimulation pulse width, and electrical stimulation frequency.

[0098] like Figure 4 As shown, the motion posture information includes: wrist flexion, wrist extension, wrist pronation, wrist supination monitored by angle sensors 1 and 2 , and elbow flexion and elbow extension monitored by angle sensor 3 .

[0099] The electrical stimulation module 3 includes 8 electrical stimulation generation circuits and a ring electrode. The electrical stimulation generation circuit includes a unipolar to bipolar circuit and a voltage-controlled constant current source circuit. The ring electrode contains 8 channels (numbered CH1 to CH8), and the circuit is connected to the 8 channels contained in the ring stimulation electrode. The amplitude, pulse width, frequency, and timing of the biphasic constant pulse current signal can be adjusted through the WIFI module through the mobile device.

[0100] The WIFI module can wirelessly transmit the electrical stimulation parameters and joint angles of the electrical stimulation module to the mobile device for display. The user of the neural electrical stimulation system can also set the output electrical stimulation parameters from the mobile device and transmit them to the microcontroller through the WIFI module.

[0101] The process of encoding motion posture information based on alternative wrist and elbow proprioception reconstruction method includes:

[0102] 1) The correspondence between wrist flexion or wrist extension and the electrical stimulation pattern in the movement posture information includes:

[0103] like Figure 5As shown, when the prosthesis is in a straight state, the outward direction perpendicular to the palm is the positive direction of the Y axis, the middle axis of the upper arm is the Z axis, the direction pointing to the fingertips is the positive direction of the Z axis, the direction perpendicular to both the Y and Z axes is the X axis, and the direction perpendicular to the thumb is the positive direction of the X axis. A spatial rectangular coordinate system is established, and the angle θ1 of the prosthetic wrist flexion and extension is defined as: the angle of the palm surface controlled by the prosthetic wrist flexion and extension motor in the plane where the X axis is located deviates from the Z axis, with flexion being positive and extension being negative; the wrist flexion and extension movement angle θ1 of the wrist joint is divided into 5 parts: -60°~31°, -30°~0°, 0°, 0°~30°, and 31°~60°. When the movement posture information is in the wrist straight state, channels CH1 and CH5 are selected for simultaneous output; when the movement posture information is in the wrist flexion state, channels CH2 and CH4 are selected for output within the angle θ1 range of 0° to 30°, and channel CH3 is selected for output within the angle θ1 range of 31° to 60°; when the movement posture information is in the wrist extension state, channels CH6 and CH8 are selected for output within the angle θ1 range of 0° to -30°, and channel CH7 is selected for output within the angle θ1 range of -31° to -60°; the stimulation current amplitude is a constant, and the specific value is determined and set in advance based on the pre-measured sensory threshold and pain threshold results of the disabled subjects and the sensory sensitivity level of the disabled subjects' residual limbs. When the wrist joint starts to flex / extend from a certain angle, the channel corresponding to the angle is selected to start outputting electrical stimulation. For example, when the wrist joint flexes and extends at a small angle (starting from a straight state), the channels corresponding to the angle range start to output electrical stimulation in sequence. When the wrist is flexed, the output order is CH1 and CH5, CH2 and CH4, CH3; when the wrist is extended, the output order is CH1 and CH5, CH6 and CH8, CH7.

[0104] For example, when the wrist joint is flexed and extended at a large angle (after flexion / extension, continue flexion and extension from this state), the channels corresponding to the angle range start to output electrical stimulation in sequence. When the wrist is flexed, the output sequence is CH7, CH6 and CH8, CH1 and CH5, CH2 and CH4, CH3; when the wrist is extended, the output sequence is opposite to that of wrist flexion.

[0105] 2) The correspondence between wrist pronation, wrist supination and electrical stimulation mode in the movement posture information includes:

[0106] When the prosthesis is in a straight state, a spatial rectangular coordinate system is established with the direction perpendicular to the palm outward as the positive direction of the Y axis, the middle axis of the upper arm as the Z axis, the direction pointing to the fingertips as the positive direction of the Z axis, the direction perpendicular to both the Y and Z axes as the X axis, and the direction perpendicular to the thumb as the positive direction of the X axis. The forward rotation of the thumb is called pronation, and the backward rotation of the thumb is called supination. The angle θ2 of the prosthetic wrist rotation is defined as: the angle between the perpendicular palm outward vector and the y axis when the prosthesis rotates around the middle axis of the forearm (Z axis); the angles θ2 of supination and pronation are divided into 5 parts: 0°~45°, 46°~90°, 91°~135°, and 135°~180°. When the wrist joint is in the neutral position, which is recorded as 0°, CH1 is selected to output electrical stimulation; when the wrist joint performs pronation, the left wrist is output in the counterclockwise direction, and electrical stimulation is output in the channels corresponding to the angle from CH1 to CH5, and the right wrist is output in the clockwise direction; when the wrist joint performs supination, electrical stimulation is output in the rotation direction of the wrist joint from CH5 to CH1 in sequence, the left wrist is output in the clockwise direction, and the right wrist is output in the counterclockwise direction.

[0107] For example, when the left wrist joint rotates at a large angle (starting from a straight state), the channels in the corresponding angle range output electrical stimulation in sequence. When the wrist is pronated, the output sequence is CH1, CH2, CH3, CH4, CH5; when it is supinated, the output sequence is CH5, CH4, CH3, CH2, CH1. The order of the right wrist joint is opposite to that of the left hand, so it will not be described here.

[0108] For example, when the left wrist joint rotates at a small angle (after pronation to 90°, the corresponding output channel is CH3, and the rotation continues from this state), the channels in the corresponding angle range output electrical stimulation in sequence. When the wrist is pronated, the output sequence is CH3, CH4, CH5; when the wrist is supinated, the output sequence is CH3, CH2, CH1; the output sequence of the right hand is opposite to that of the left hand. When the wrist joint is at any angle, the rotation mode is the same as this example.

[0109] 3) The correspondence between elbow flexion, elbow extension and electrical stimulation mode in the movement posture information includes:

[0110] The elbow straight state is defined as: when the axis of the forearm and the axis of the upper arm are on the same straight line; the angle θ3 of the prosthetic elbow flexion and extension is defined as: the angle between the axis of the forearm and the axis of the upper arm;

[0111] like Figure 6As shown in the figure, the elbow flexion and extension angle θ3 is divided into 4 parts: 0°, 0°~45°, 46°~90°, 91°~135°, and the corresponding output channels are: CH7, CH6 and CH8, CH1 and CH5, CH2 and CH4. When the movement posture information is the elbow straight state, the CH7 channel outputs; when the elbow is flexed, the corresponding channel is selected in sequence according to the movement angle from 0° to 135° to output electrical stimulation; when the elbow is extended, the stimulation channel sequence direction is opposite to that when the elbow is flexed, and the stimulation current amplitude is a constant, and the specific value range is 0~8mA, which is determined and set in advance based on the pre-measured sensory threshold and pain threshold results of the disabled subjects and the sensory sensitivity level of the residual limbs of the disabled subjects.

[0112] like Figure 2 As shown, the application process of the neural electrical stimulation system for prosthetic wrist and elbow joint angle feedback of the present invention in an example includes:

[0113] The messenger wears the prosthetic wrist and elbow joint angle feedback neural electrical stimulation system, and a ring electrode containing 8 electrode stimulation channels is attached to his limbs. Figure 3 As shown, CH1 is placed on the belly of the biceps brachii muscle of the upper arm, and CH5 is placed on the belly of the triceps brachii muscle of the upper arm. The user selects the wrist or elbow feedback mode of the prosthetic movement.

[0114] Angle sensors are installed on the wrist and elbow of the prosthesis. The angle sensors monitor the movement posture information of the prosthesis in real time and send the posture information in the corresponding mode to the microcontroller.

[0115] The microcontroller reads and analyzes the movement posture information, encodes the movement posture information according to the alternative wrist and elbow proprioception reconstruction method, selects and activates the corresponding pulse channel, and outputs the voltage pulse signal obtained by the encoding conversion to the corresponding electrical stimulation module.

[0116] After receiving the voltage pulse signal, the pulse channel is processed by the voltage-controlled constant current source circuit and converted into a single-phase constant current pulse signal, which is then processed by the unipolar to bipolar circuit to output a biphase constant pulse current signal.

[0117] The electrodes act on the user's skin surface to produce a corresponding alternative sensory pattern.

[0118] In this example, the waveform of the signal stimulus is as follows Figure 6 As shown, the output pulse width is a bidirectional square wave of 400us, with the negative wave going first and the delay between the positive and negative waves being 100μs.

Claims

1. A method for reconstructing alternative wrist and elbow proprioception based on a neural electrical stimulation system, characterized in that: The neural electrical stimulation system includes an electrical stimulation module, an angle sensor, a data transmission module, a microcontroller and a mobile terminal; The alternative wrist and elbow proprioception reconstruction method includes the following steps: 1) A prosthesis user without phantom limb sensation wears the prosthesis, and places stimulation electrodes on the skin surface of the upper arm stump. A portable electrical stimulation module connected to the stimulation electrodes is installed in the receiving cavity of the prosthesis; an angle sensor is placed inside the prosthesis; 2) The angle sensor monitors the limb movement posture information of the prosthesis user without phantom limb sensation and transmits it to the microcontroller; 3) The microcontroller generates an electrical stimulation pattern according to the motion posture information or the electrical stimulation parameter information; The electrical stimulation mode includes the electrical stimulation channel number, electrical stimulation timing, electrical stimulation amplitude, electrical stimulation pulse width, and electrical stimulation frequency; the electrical stimulation timing includes the order in which the electrical stimulation channels generate stimulation signals; Among the electrical stimulation parameters, the electrical stimulation pulse width and the electrical stimulation frequency are adjusted according to the sensory function of the prosthesis user without phantom limb sensation; 4) the microcontroller controls the electrical stimulation module to generate electrical stimulation for the prosthetic user without phantom limb sensation according to the electrical stimulation pattern, and transmits the electrical stimulation pattern to the mobile terminal for display through the data transmission module; The electrical stimulation module includes n electrical stimulation generation circuits and ring electrodes; n is a natural number; The ring electrode includes n electrodes, and the channels of the electrode output signals are respectively recorded as CH1, CH2, ..., CHn; one electrode is connected to one electrical stimulation generation circuit; The electrical stimulation generating circuit comprises a unipolar to bipolar conversion circuit and a voltage-controlled constant current source circuit; The unipolar-to-bipolar circuit converts the received single-phase constant current pulse signal into a biphase constant pulse current signal, and outputs the signal to the voltage-controlled constant current source circuit; The voltage-controlled constant current source circuit is then used to isolate the influence of human body impedance on the current signal, and transmit the electrical stimulation signal to the ring electrode, and the ring electrode is used to electrically stimulate the prosthesis user without phantom limb sensation; The biphasic constant pulse current signal is a biphasic current pulse signal which is first negative and then positive; The ring electrode includes 8 channels, which are respectively denoted as CH1, CH2, ..., CH8; The determining factors of the electrical stimulation channel number and the electrical stimulation intensity parameters include the wrist joint flexion and extension movement angle, the wrist joint rotation angle, and the elbow joint flexion and extension movement angle; When the prosthesis is in a straight state, the direction perpendicular to the palm is the positive direction of the Y axis, the middle axis of the upper arm is the Z axis, the direction pointing to the fingertips is the positive direction of the Z axis, the direction perpendicular to both the Y and Z axes is the X axis, and the direction perpendicular to the thumb is the positive direction of the X axis. A spatial rectangular coordinate system is established, and the angle θ1 of the prosthetic wrist flexion and extension is defined as: the angle of the palm surface controlled by the prosthetic wrist flexion and extension motor in the plane where the X axis is located, which deviates from the Z axis. Flexion is positive, and extension is negative. When the motion posture information is in the wrist straight state, that is, θ1 = 0°, the selected electrical stimulation channel numbers include channel CH1 and channel CH5; channel CH1 and channel CH5 output electrical stimulation at the same time; When the motion posture information is in the wrist flexion state, when the angle θ1 is between 0° and 30°, the selected electrical stimulation channel numbers include channel CH2 and channel CH4, and channel CH2 and channel CH4 output electrical stimulation simultaneously; When the movement posture information is in the wrist flexion state, when the angle θ1 is between 31° and 60°, the selected electrical stimulation channel number includes channel CH3; When the motion posture information is in the wrist extension state and the angle θ1 is between 0° and -30°, the selected electrical stimulation channel numbers include channel CH6 and channel CH8, and channel CH6 and channel CH8 output electrical stimulation simultaneously; When the movement posture information is in the wrist extension state and the angle θ1 is between -31° and -60°, the selected electrical stimulation channel number includes channel CH7; When the prosthesis is in a straight state, the direction perpendicular to the palm outward is the positive direction of the Y axis, the middle axis of the upper arm is the Z axis, the direction pointing to the fingertips is the positive direction of the Z axis, the direction perpendicular to both the Y and Z axes is the X axis, and the direction perpendicular to the thumb is the positive direction of the X axis. A spatial rectangular coordinate system is established. The forward rotation of the thumb is called pronation, and the backward rotation of the thumb is called supination. The angle θ2 of the prosthetic wrist rotation is defined as: the angle between the vertical palm outward vector and the y axis when the prosthesis rotates around the middle axis of the forearm, that is, around the Z axis; When the wrist joint is in a straight wrist state, that is, θ2 = 0°, the selected electrical stimulation channel numbers include channel CH1; When the wrist joint performs pronation, the selected electrical stimulation channel numbers include channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5; channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5 output electrical stimulation in sequence; When the wrist joint performs supination movement, the selected electrical stimulation channel numbers include channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5; channel CH5, channel CH4, channel CH3, channel CH2, and channel CH1 output electrical stimulation in sequence; The elbow straight state is defined as: when the axis of the forearm and the axis of the upper arm are on the same straight line; The angle θ3 of prosthetic elbow flexion and extension is defined as: the angle between the axis of the forearm and the axis of the upper arm; When the movement posture information is the elbow straight state, that is, θ3 = 0°, the selected electrical stimulation channel number includes channel CH7; When the movement posture information is elbow flexion and the angle θ3 is between 0° and 45°, the selected electrical stimulation channel numbers include channel CH6 and channel CH8, and channel CH6 and channel CH8 output electrical stimulation simultaneously; When the movement posture information is elbow flexion and the angle θ3 is between 46° and 90°, the selected electrical stimulation channel numbers include channel CH1 and channel CH5, and channel CH1 and channel CH5 output electrical stimulation simultaneously; When the movement posture information is elbow flexion and the angle θ3 is between 91° and 135°, the selected electrical stimulation channel numbers include channel CH2 and channel CH4, and channel CH2 and channel CH4 output electrical stimulation simultaneously; When the movement posture information is elbow extension and the angle θ3 is between 0° and 45°, the selected electrical stimulation channel numbers include channel CH8 and channel CH6, and channel CH8 and channel CH6 output electrical stimulation simultaneously; When the movement posture information is elbow extension and the angle θ3 is between 46° and 90°, the selected electrical stimulation channel numbers include channel CH5 and channel CH1, and channel CH5 and channel CH1 output electrical stimulation simultaneously; When the movement posture information is elbow extension and the angle θ3 is between 91° and 135°, the selected electrical stimulation channel numbers include channel CH4 and channel CH2, and channel CH4 and channel CH2 output electrical stimulation simultaneously; The electrical stimulation parameter information is set by a prosthesis user without phantom limb sensation on a mobile terminal, and is transmitted to the microcontroller by the mobile terminal through a data transmission module; The movement posture information includes wrist flexion, wrist extension, wrist pronation, wrist supination, elbow flexion, and elbow extension; The biphasic constant pulse current signal is a biphasic current pulse signal which is first negative and then positive; The amplitude, pulse width and frequency of voltage pulse signal and bi-phase constant pulse current signal are adjustable; The current range of the biphasic constant pulse current signal stimulation is 0-8 mA, the frequency range is 100-500 Hz, and the pulse width range is 100-500 us.

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