CN110946683A - Electric stimulation driving method and system for artificial finger tip pressure and joint angle feedback - Google Patents
Electric stimulation driving method and system for artificial finger tip pressure and joint angle feedback Download PDFInfo
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- CN110946683A CN110946683A CN201911167807.3A CN201911167807A CN110946683A CN 110946683 A CN110946683 A CN 110946683A CN 201911167807 A CN201911167807 A CN 201911167807A CN 110946683 A CN110946683 A CN 110946683A
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/50—Prostheses not implantable in the body
- A61F2/68—Operating or control means
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/50—Prostheses not implantable in the body
- A61F2/68—Operating or control means
- A61F2002/6827—Feedback system for providing user sensation, e.g. by force, contact or position
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Abstract
The invention discloses an electric stimulation driving method and system for feedback of pressure and joint angle of a fake finger tip, wherein the system comprises a pressure angle measuring module and an electric stimulation controller, and the pressure angle measuring module comprises an optical fiber sensor; the optical fiber sensor is used for measuring the pressure and the angle of each finger of the fake fingertip in real time and sending the pressure and the angle to the electrical stimulation controller; the electric stimulation controller is used for generating constant current with specific stimulation frequency through receiving the angle of each finger joint and the pressure value of the finger tip and through a preset mapping relation, and stimulating the upper limb of the user through an electrode fixed on the cuff. The system can enable a user to better control the artificial limb to complete daily life actions, and can reduce the rejection psychology of the user to the artificial limb.
Description
Technical Field
The invention relates to the technical field of touch feedback, in particular to an electric stimulation driving method and system for artificial finger tip pressure and joint angle feedback.
Background
The existing artificial limb can meet daily requirements, but generally lacks a feedback device capable of feeding back information such as pressure on the tip of the artificial finger to a user, and lacks a feedback device for the user, so that the information such as the pressure and the temperature on the tip of the artificial finger cannot be obtained in real time, on one hand, the control of the artificial limb cannot form closed-loop control, the control accuracy is reduced, and on the other hand, the psychological conflict can be generated for the user due to the loss of the information of the pressure and the temperature by the user. Therefore, the feedback device on the prosthesis is very important.
The existing feedback device provides sensory feedback by an artificial sensory stimulator through electrical signals, vibration signals and visual signals as described in patent CN103720528, but a method for realizing stimulation corresponding to sensation is not specifically described; the myoelectric artificial hand tactile feedback method disclosed in patent CN102379760A is capable of feeding back forces in six directions of the whole artificial hand, but cannot realize the force of each finger, and uses vibration mode feedback, which consumes high energy and is not suitable for long-term use. The invention provides an electric stimulation driving method and system for feeding back the pressure of a tip of a prosthetic finger and the angle of a joint, which can feed back the pressure of the tip of the prosthetic finger and the angle of the joint of the prosthetic finger to a prosthetic limb user.
Disclosure of Invention
In order to solve the defects of psychological conflict of a user and low control precision of an artificial limb caused by the fact that the existing artificial limb lacks a feedback device, the invention provides an electric stimulation driving method and system for feedback of the pressure of a tip of the artificial finger and the angle of a joint. The system can enable a user to better control the artificial limb to complete daily life actions, and can reduce the rejection psychology of the user to the artificial limb.
In order to achieve the purpose, the invention adopts the following technical scheme:
an electric stimulation driving system for feeding back the pressure of a false finger tip and the joint angle comprises a pressure angle measuring module and an electric stimulation controller, wherein the pressure angle measuring module comprises an optical fiber sensor;
the optical fiber sensor is used for measuring the pressure and the angle of each finger of the fake fingertip in real time and sending the pressure and the angle to the electrical stimulation controller;
the electric stimulation controller is used for receiving the angle of each finger joint and the pressure value of the finger tip, generating constant current with specific stimulation frequency through a preset mapping relation, and stimulating the upper limb of the user through an electrode fixed on the cuff.
As a further improvement of the invention, the electrodes are divided into positive and negative electrodes which are respectively connected with the positive and negative ends of the output channel of the electrical stimulation controller, and each output channel of the electrical stimulation controller is connected with a pair of positive and negative electrodes which are correspondingly distributed up and down.
As a further improvement of the invention, when the cuff is tied on the upper limb big arm of the user, the positive and negative electrodes are distributed along the axial direction of the upper limb big arm and are distributed at equal intervals in the circumferential direction of the upper limb big arm.
As a further improvement of the invention, the optical fiber sensor is fixed on the five fingers on the front surface of the artificial hand, deforms along with the bending of the fingers and deforms along with the change of the pressure.
As a further improvement of the invention, the electrical stimulation controller outputs multi-channel bipolar pulse constant current with different frequencies and amplitudes.
As a further improvement of the invention, the electrical stimulation controller comprises a power module, a bluetooth module, a controller module, a digital-to-analog conversion module, a voltage-controlled constant current source module, a current polarity conversion module and a current-limiting protection module; the controller module, the digital-to-analog conversion module, the voltage-controlled constant current source module, the current polarity conversion module and the current-limiting protection module are all connected with the power supply module, and the controller module is connected with the Bluetooth module;
the power supply module is used for supplying power to each module;
the Bluetooth module is used for receiving the finger pressure and joint angle value of each finger tip;
the controller module is used for generating a control waveform command;
the digital-to-analog conversion module is used for converting a digital signal into an analog signal;
the voltage-controlled constant current source module is used for outputting constant current;
the polarity conversion module is used for controlling the polarity of the output current;
the current-limiting protection module is used for limiting the amplitude of the output current.
As a further improvement of the invention, the electric stimulation controller grades the pressure and angle values according to the obtained pressure and angle values, and sets 7 current stimulation grades with stimulation frequencies lower than 100Hz, wherein the current stimulation grades are respectively 1Hz, 2Hz, 4Hz, 8Hz, 16Hz, 32Hz and 64Hz, and the current amplitude is 7 mA.
As a further improvement of the present invention, the 7 levels of current stimulation, the level division and mapping of knuckle angle and fingertip pressure are as follows:
1) the method comprises the following steps of (1) carrying out grade division on angles of the artificial hand, wherein the rotation range of five finger joints of the artificial hand is 0-90 degrees, the artificial hand is divided into three grades, and the angle grade is one in the range of 0-30 degrees; the angle grade is two within the range of 31-60 degrees; the angle grade is three within the range of 61-90 degrees;
2) grading the pressure of the tip of the artificial finger, wherein the pressure grade is 1 in the range of 0-2N; pressure grade 2 in the range of 2-4N; pressure grade 3 in the range of 4-6N; the pressure grade is 4 when the range of 6N is more than the range of 6N;
the seven levels correspond to frequency currents of 1Hz, 2Hz, 4Hz, 8Hz, 16Hz, 32Hz and 64Hz output by the electrical stimulation controller respectively, when the measured pressure and joint angle are positioned at one of the seven levels, the corresponding channel of the electrical stimulation controller is controlled to output the current of the corresponding frequency, the thumb corresponds to the stimulation channel 1, the index finger corresponds to the stimulation channel 2, the middle finger corresponds to the stimulation channel 3, the ring finger corresponds to the stimulation channel 4 and the little finger corresponds to the stimulation channel 5; meanwhile, when the fingertip does not generate pressure, only the finger joint angle is fed back; when the fingertip generates pressure, only the pressure value is fed back; therefore, the user can know various information on the artificial hand to form closed loop feedback.
A driving method of an electric stimulation driving system for feeding back pressure and joint angle of a fake finger tip comprises the following steps:
the electrical stimulation controller is provided with 5 stimulation channels, and the channel 1 corresponds to the thumb; the channel 2 corresponds to an index finger; the channel 3 corresponds to a middle finger; the channel 4 corresponds to a ring finger; the channel 5 corresponds to a little finger; when the artificial hand does not grab the object and the pressure value of the fingertip is 0, the electrical stimulation is only directed at the corresponding angle value, and 3 levels of the angle of the artificial finger respectively correspond to the first three stimulation frequencies of the stimulation frequencies; when the artificial hand grabs an article and generates fingertip pressure, the stimulation is only directed at the corresponding fingertip pressure value, and 4 levels of the pressure of the artificial finger tip respectively correspond to the last four stimulation frequencies of the stimulation frequencies; when the pressure or angle value is in a certain level, the electric stimulation controller outputs current with corresponding frequency.
As a further improvement of the present invention, after the electrical stimulation controller is powered on, the specific control flow is as follows:
1) enabling a clock;
2) the serial port communication judges whether data is received, if the data is not received, the data is continuously waited, if the data is received, the data enters an interrupt, the received 16-bit data, namely 2 bytes, is stored, and the interrupt is closed;
3) on the basis of the received 16-bit data,
if the value of the lower 4 bits of the 1 st byte is 1, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 1;
if the value of the lower 4 bits of the 1 st byte is 2, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 2;
if the value of the lower 4 bits of the 1 st byte is 3, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 3;
if the value of the lower 4 bits of the 1 st byte is 4, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 4;
if the value of the lower 4 bits of the 1 st byte is 5, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 5;
4) according to the received 16-bit data, if the value of the first byte is 4 high bits and is 1, the value is a pressure value, the actual pressure value is 8 low bits and is 0.1, according to the mapping relation, the channel is graded, and the channel stimulation current frequency is set; if the high 4-bit numerical value of the first byte is 2, the value is an angle value, the actual angle value is the low 8-bit numerical value of the received data, the levels are divided according to the mapping relation, the stimulation current frequency of the channel is set, and the stimulation current is output;
when the upper limb of the user feels current stimulation, the level of the stimulation frequency and the stimulation channel are judged, the corresponding pressure or angle level is identified according to the mapping relation, and the fingertip pressure and the finger joint angle of the artificial hand are identified.
Compared with the prior art, the invention has the following technical effects:
the electric stimulation driving system can establish a mapping relation between the pressure and the joint angle measured on the artificial fingertip and the current stimulation with different frequencies, and feed the mapping relation back to a user in an electric stimulation mode, and the user can distinguish the pressure and the joint angle through the mapping relation, so that the user can better control the artificial limb to finish daily life actions, and the rejection psychology of the user to the artificial limb can be reduced. Compared with the defects that the traditional artificial limb lacks a feedback device and causes psychological conflict of a user and the control precision of the artificial limb is low, the invention provides the feedback device of fingertip pressure and finger joint angle, so that the control of the artificial limb by the user is more accurate and the interaction is more natural; the device can improve the psychological feeling of the prosthesis user, reduce the repulsion psychology of the prosthesis user to the prosthesis, ensure that the prosthesis is more friendly to use, and also provide the joint feedback of the joint of the artificial finger and the pressure of the fingertip.
The invention designs a control flow on the basis of completing an electrical stimulation hardware system, wherein a current stimulation system mainly makes a decision according to the pressure and the angle of each finger transmitted by a signal demodulator, outputs stimulation pulses with specific frequency, judges the level of stimulation frequency and the stimulation channel when the upper limb of a user feels current stimulation, and can identify the corresponding pressure or angle level according to the mapping relation, namely, can identify the fingertip pressure and the finger joint angle of a prosthetic hand. The system aims at the problem that the angle information of the artificial finger is easy to ignore, and mapping coding is carried out by combining fingertip pressure, so that the control of a user on the artificial limb is more accurate, and the interaction is more natural.
Drawings
FIG. 1 is a schematic diagram of an electrical stimulation driving system for artificial finger tip pressure and joint angle feedback;
FIG. 2 is the location of the stimulation electrodes in the cuff;
wherein: 1. an optical fiber sensor; 2. a signal demodulator; 3. a prosthetic palm; 4. the user's upper limb forearm; 5. the upper limb of the user; 6. a cuff; 7. an electrical stimulation controller;
FIG. 3 is a block diagram of an electrical stimulation controller;
FIG. 4 is a circuit diagram of a voltage controlled constant current source module;
FIG. 5 is a circuit diagram of a polarity conversion module;
fig. 6 is a control flow chart of the electrical stimulation controller.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the present disclosure. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Various structural schematics according to the disclosed embodiments of the invention are shown in the drawings. The figures are not drawn to scale, wherein certain details are exaggerated and possibly omitted for clarity of presentation. The shapes of various regions, layers and their relative sizes and positional relationships shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, according to actual needs.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
As shown in fig. 1 to 6, the present invention is an electrical stimulation driving method and system for feedback of pressure and joint angle of a prosthetic finger tip, mainly comprising a pressure angle measuring module and an electrical stimulation controller; the pressure angle measuring module comprises an optical fiber sensor and a signal demodulator, the optical fiber sensor is used for measuring the pressure and the angle of each finger of the fake fingertip in real time, and the signal is demodulated into an actual pressure and an actual angle value through the signal demodulator and is sent to the electrical stimulation controller through Bluetooth; the electric stimulation controller can output 5 channels of bipolar pulse constant current with different frequencies and amplitudes, the electric stimulation control module comprises a power supply module, a Bluetooth module, a controller module, a digital-to-analog conversion module, a voltage-controlled constant current source module, a current polarity conversion module and a current-limiting protection module, the power supply module is used for supplying power to each module, the Bluetooth module is used for receiving each finger pressure and joint angle value of a fake finger tip sent by a signal demodulator, the controller module is used for generating a control waveform command, the digital-to-analog conversion module is used for converting a digital signal into an analog signal, the voltage-controlled constant current source module is used for outputting constant current, the polarity conversion module is used for controlling the polarity of output current, and the current-limiting.
The whole system firstly measures the pressure of the artificial finger tip and the angle value of the joint by the optical fiber sensor and sends the values to the electrical stimulation controller, and the electrical stimulation controller grades the values according to the obtained pressure and angle values. The normal human skin can sense and recognize the electric stimulation with different frequencies, so the fingertip pressure and the joint angle are fed back through the human body sensing the electric stimulation, but the resolution ratio of the electric stimulation with too close frequencies is not high, and simultaneously the pricking feeling can be generated by the stimulation with too high frequencies, considering this, in order to ensure the recognition accuracy and the feeling of the human body to different stimulation frequencies, only 7 current stimulation grades with different frequencies are set, wherein the stimulation frequencies of the 7 grades are respectively 1Hz, 2Hz, 4Hz, 8Hz, 16Hz, 32Hz and 64Hz, the current amplitude is 7mA, and simultaneously the grade division and the mapping relation of the current stimulation, the finger joint angle and the fingertip pressure of the 7 grades are as follows:
1. the method comprises the following steps of (1) carrying out grade division on angles of the artificial hand, wherein the rotation range of five finger joints of the artificial hand is 0-90 degrees, the artificial hand is divided into three grades, and the angle grade is one in the range of 0-30 degrees; the angle grade is two within the range of 31-60 degrees; the angle grade is three within the range of 61-90 degrees;
2. grading the pressure of the tip of the artificial finger, wherein the pressure grade is one in the range of 0-2N; the pressure grade is two in the range of 2-4N; the pressure grade is three in the range of 4-6N; the pressure grade is 4 when the range of 6N is more than the range of 6N;
3. and respectively corresponding the seven levels to 1Hz, 2Hz, 4Hz, 8Hz, 16Hz, 32Hz and 64Hz frequency currents output by the electrical stimulation controller, controlling the corresponding channels of the electrical stimulation controller to output the currents with the corresponding frequencies when the measured pressure and joint angle are positioned at one of the seven levels, wherein the thumb corresponds to the stimulation channel 1, the index finger corresponds to the stimulation channel 2, the middle finger corresponds to the stimulation channel 3, the ring finger corresponds to the stimulation channel 4 and the little finger corresponds to the stimulation channel 5. Meanwhile, when the fingertip does not generate pressure, only the finger joint angle is fed back; when the fingertip generates pressure, only the pressure value is fed back. Therefore, the user can know various information on the artificial hand to form closed loop feedback.
The invention is described in detail below with reference to specific embodiments and the attached drawings:
examples
Referring to the schematic structural diagram shown in fig. 1, the system measures the joint angle and fingertip pressure of a prosthetic finger in real time through an optical fiber sensor 1 arranged on the five fingers on the front side of the prosthetic hand, converts the joint angle and fingertip pressure into photoelectric signals, transmits the photoelectric signals to a signal demodulator 2, the signal demodulator 2 converts the photoelectric signals into angle and pressure values through decoding, then transmits the values to an electrical stimulation controller 7 through Bluetooth, the electrical stimulation controller receives the joint angle and fingertip pressure values through a Bluetooth module, and through a preset mapping relation, the electrical stimulation controller generates constant current with specific stimulation frequency, and stimulates the upper limb of a user through a positive electrode and a negative electrode fixed on a cuff 6.
The cuff is tied on the upper limb of a user, the user can feel current stimulation with different frequencies on the upper limb, and the user can identify the joint angle and the fingertip pressure of the artificial finger through a preset mapping relation according to the sensed stimulation frequency, so that the user can adjust the control on the artificial limb in time, and the closed-loop control on the artificial limb is achieved.
Fig. 2 shows the fixed position of the electrode in the cuff, the electrode is divided into a positive electrode and a negative electrode which are respectively connected with the positive end and the negative end of the output channel of the electrical stimulation controller, each output channel of the electrical stimulation controller is connected with a pair of positive and negative electrodes which are distributed up and down correspondingly, and the positive and negative electrodes respectively correspond to the channels 1 to 5 from left to right. When the cuff is tied on the upper limb big arm of a user, the positive and negative electrodes are distributed along the axial direction of the upper limb big arm and are distributed at equal intervals in the circumferential direction of the upper limb big arm.
The optical fiber sensor 1 is fixed on the five fingers on the front face of the artificial hand, deforms along with the bending of the fingers and deforms along with the change of the pressure, the deformation can change the optical signal transmitted to the signal demodulator by the optical fiber sensor, and the change can be demodulated into the actual joint angle of the tip of the artificial finger and the actual joint angle of the finger through the signal demodulator, so that the pressure of the tip of the artificial finger and the joint angle of the finger can be measured. After the signal demodulator obtains the actual pressure and angle values, the signal demodulator sends the measured pressure of the artificial finger tip and the measured angle of the finger joint to the current stimulator through the Bluetooth module, and the coding format of the information is as follows:
1. the bluetooth communication uses 2 bytes, i.e. 16 bits, as a unit, the upper 8 bits are the 1 st byte, and the lower 8 bits are the 2 nd byte.
2. If the pressure value is 0, only sending the angle value of the fake finger; if the pressure value is not 0, only sending the pressure value of the fake finger tip;
3. if the transmission value is a pressure value, the 1 st byte high 4-bit value is 0001; if the transmission numerical value is an angle value, the high 4 bits of the 1 st byte are 0010;
4. if the transmission value is a thumb-related value, the 1 st byte is lower by 4 bits 0001; if the transmission numerical value is the index finger related numerical value, the 1 st byte is 0010 in the lower 4 bits; if the transmission value is the middle finger related value, the 1 st byte is 0011 with 4 lower bits; if the transmission numerical value is a ring finger related numerical value, 0100 is 4 bits lower than the 1 st byte; if the transmission numerical value is a little finger correlation numerical value, 0101 is the lower 4 bits of the 1 st byte;
5. if the transmission numerical value is an angle value, the 2 nd byte numerical value is an actual angle value; if the transmission value is the pressure value, the 2 nd byte value is the actual pressure value multiplied by 100, that is, the transmission value is the pressure value
Actual pressure value is 0.1 as transmission value
The above is the transmission coding mode.
Fig. 3 is a structural diagram of an electrical stimulation controller. The system comprises a power module, a Bluetooth module, a controller module, a digital-to-analog conversion module, a voltage-controlled constant current source module, a current polarity conversion module and a current-limiting protection module. The controller sets output voltage through communication between the SPI and the digital-to-analog conversion module, the voltage is output to the voltage-controlled constant current source module to control and output current with certain amplitude, then the current is output to the polarity conversion module to change the polarity of the current, the amplitude of the output current is limited through the current-limiting protection module to ensure safe use, and finally the current with specific frequency is output to the electrode to stimulate the upper limb of a user. The electrical stimulation controller has the following specific functions:
1. the power module is used for converting an input power supply into a power supply with rated voltage required by each module, the module uses an 8V lithium battery as the input power supply and simultaneously comprises two voltage boosting units and two voltage reducing units, the voltage reducing units convert the 8V power supply into a 3.3V power supply through an ASM117-3.3V chip, and the voltage boosting modules convert the 8V power supply into 15V and 40V power supplies for each module respectively by using two XL6019 chips.
2. The controller module is mainly used for controlling current polarity conversion and controlling the output voltage, an STM32F405RG chip is used as a main control chip of the controller module, the controller module is connected with the digital-to-analog conversion module and the current polarity control module, the controller module is communicated with the digital-to-analog conversion module through the SPI, and the output voltage of the digital-to-analog conversion module is set; the polarity of the output current is controlled by setting a pin to output different PWM waves to a current polarity module.
3. The digital-to-analog conversion module uses an AD5721R chip, is mainly used for converting a digital signal sent from a controller into an actual analog voltage signal, and is used for controlling the output current of the voltage-controlled constant current source module.
4. The voltage-controlled constant current source module converts the output voltage of the digital-to-analog conversion module into constant current for output by using a Wilson constant current source circuit. Referring to fig. 4, the circuit is a symmetrical circuit, T0, T1, T2 are three PNP transistors with the same parameters, T3 is an NPN transistor, T4 is an operational amplifier, IloadIs equal to IR1. The triode is connected with the 40V constant voltage output by the power module, and the operational amplifier is connected with the 15V voltage output by the power module. The operational amplifier uses LM358 chip, the positive phase of the operational amplifier is connected with constant voltage value connected from the D/A conversion module, the negative phase is connected with emitter of T3, the output end is connected with base of T3, IR1DAC input Voltage/R1Then, Iload＝IR1DAC input Voltage/R1And further realize the output control of the voltage-controlled constant current source.
5. The polarity conversion module uses the ADG5421 gating chip to change the polarity of the current by changing the channel gating. Fig. 5 is a circuit diagram of the polarity conversion module. The pin 1 of the chip 1 is used as an output anode, the pin 1 of the chip 2 is used as an output cathode, the output of the voltage-controlled constant current source module is connected to the pin 2 of the chip 1 and the pin 8 of the chip 2, the pin 8 of the chip 1 and the pin 2 of the chip 2 are connected to the ground, the pins 6 of the chips 1 and 2 are connected to the PWM output pin of the STM32F405, and the current output polarity is controlled by using PWM. When the PWM output by the pin 6 is at a low level, the current flows from OUT _1 to OUT _ 2; when pin 6 is at a high level, current flows from OUT _2 to OUT _1, thereby controlling the polarity of the current.
6. The current limiting protection module is used for controlling the amplitude of output current, and a PTC self-recovery current wire patch of 36V/50mA is connected with the output in series to play a protection role.
7. The Bluetooth module uses an HC-06 module and is mainly used for receiving the pressure of the fake finger tip and the angle of the finger joint measured by the sensor and controlling the electric stimulation controller to output currents with different stimulation frequencies according to the received pressure and angle values.
And designing a control flow on the basis of the completed electrical stimulation hardware system. The current stimulation system mainly makes a decision according to the pressure and the angle of each finger transmitted by the signal demodulator and outputs stimulation pulses with specific frequency, the system performs mapping coding by combining the fingertip pressure aiming at the angle information which is easy to be ignored by a human, and the coding steps are as follows:
1. the electrical stimulation frequency is selected from 7 specific frequencies, namely 1Hz, 2Hz, 4Hz, 8Hz, 16Hz, 32Hz and 64Hz, so as to enable a user to distinguish the 7 different degrees of stimulation.
2. The angles of the artificial fingers are classified into three grades, wherein the rotating ranges of five knuckle joints of the artificial fingers are between 0 and 90 degrees, and the range of 0 to 30 degrees is an angle grade I; the angle grade is two within the range of 31-60 degrees; the angle grade is three within the range of 61-90 degrees;
3. grading the pressure of the tip of the artificial finger, wherein the pressure grade is one in the range of 0-2N; the pressure grade is two in the range of 2-4N; the pressure grade is three in the range of 4-6N; the pressure grade is 4 when the range of 6N is more than the range of 6N;
4. the electrical stimulation controller is provided with 5 stimulation channels, and the channel 1 corresponds to the thumb; the channel 2 corresponds to an index finger; the channel 3 corresponds to a middle finger; the channel 4 corresponds to a ring finger; the channel 5 corresponds to a little finger. When the artificial hand does not grab the object and the pressure value of the fingertip is 0, the electrical stimulation is only directed at the corresponding angle value, and 3 levels of the angle of the artificial finger respectively correspond to the first three stimulation frequencies of the stimulation frequencies; when the artificial hand grabs an article and generates fingertip pressure, the stimulation is only directed at the corresponding fingertip pressure value, and 4 levels of the pressure of the artificial finger tip respectively correspond to the last four stimulation frequencies of the stimulation frequencies. When the pressure or angle value is in a certain level, the electric stimulation controller outputs current with corresponding frequency.
The above is the coding mode between the current stimulation frequency and the actual pressure and angle.
Referring to fig. 6, after the electrical stimulation controller is powered on, the specific control flow is as follows:
1. enable clock, SPI, USART serial port, I/O.
2. The serial port communication judges whether data is received, if the data is not received, the data is continuously waited, if the data is received, the data enters an interrupt, the received 16-bit data, namely 2 bytes, is stored, and the interrupt is closed;
3. on the basis of the received 16-bit data,
if the value of the lower 4 bits of the 1 st byte is 1, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 1;
if the value of the lower 4 bits of the 1 st byte is 2, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 2;
if the value of the lower 4 bits of the 1 st byte is 3, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 3;
if the value of the lower 4 bits of the 1 st byte is 4, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 4;
if the value of the lower 4 bits of the 1 st byte is 5, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 5;
4. according to the received 16-bit data, if the value of the first byte is 4 high bits and is 1, the value is a pressure value, the actual pressure value is 8 low bits and is 0.1, according to the mapping relation, the channel is graded, and the channel stimulation current frequency is set; if the high 4-bit numerical value of the first byte is 2, the value is an angle value, the actual angle value is the low 8-bit numerical value of the received data, the levels are divided according to the mapping relation, the stimulation current frequency of the channel is set, and the stimulation current is output;
when the upper limb of the user feels current stimulation, the level of the stimulation frequency and the stimulation channel are judged, the corresponding pressure or angle level can be identified according to the mapping relation, and the fingertip pressure and the finger joint angle of the artificial hand can be identified.
Aiming at the defects of psychological conflict of users and low control precision of the artificial limb caused by the lack of a feedback device of the traditional artificial limb, the invention has the advantages that:
1. aiming at the problem that the traditional artificial limb is lack of a feedback device, the invention provides the feedback device of fingertip pressure and finger joint angle, so that the control of a user on the artificial limb is more accurate, and the interaction is more natural;
2. the device can improve the psychological feeling of the prosthesis user, reduce the psychological repulsion of the prosthesis user to the prosthesis and ensure that the prosthesis is more friendly to use.
3. Joint feedback of the artificial finger joint and the fingertip pressure can be provided.
The above is a detailed description of the present invention with reference to specific preferred embodiments, and it should not be considered that the present invention is limited to the specific embodiments, but that the present invention can be easily derived or substituted by those skilled in the art without departing from the spirit of the present invention, and all of them should be considered as falling within the scope of the patent protection defined by the claims of the present invention.
Claims (10)
1. An electric stimulation driving system for feeding back the pressure of a false finger tip and the angle of a joint is characterized by comprising a pressure angle measuring module and an electric stimulation controller, wherein the pressure angle measuring module comprises an optical fiber sensor;
the optical fiber sensor is used for measuring the pressure and the angle of each finger of the fake fingertip in real time and sending the pressure and the angle to the electrical stimulation controller;
the electric stimulation controller is used for receiving the angle of each finger joint and the pressure value of the finger tip, generating constant current with specific stimulation frequency through a preset mapping relation, and stimulating the upper limb of the user through an electrode fixed on the cuff.
2. The electric stimulation driving system for the pressure of the artificial finger tip and the joint angle feedback as claimed in claim 1, wherein the electrodes are divided into positive and negative electrodes which are respectively connected with positive and negative ends of an output channel of the electric stimulation controller, and each output channel of the electric stimulation controller is connected with a pair of positive and negative electrodes which are correspondingly distributed up and down.
3. The electrical stimulation driving system for tip pressure and joint angle feedback of a prosthetic finger as claimed in claim 1, wherein when the cuff is tied to the forearm of the user's upper limb, the positive and negative electrodes are distributed along the axial direction of the forearm of the user's upper limb and are distributed at equal intervals in the circumferential direction of the forearm of the user's upper limb.
4. The electric stimulation driving system for the tip pressure and joint angle feedback of the artificial finger as claimed in claim 1, wherein the optical fiber sensor is fixed on the five fingers on the front surface of the artificial hand, deforms along with the bending of the fingers and deforms along with the change of the pressure.
5. The electric stimulation driving system for the pressure and joint angle feedback of the artificial finger tip as claimed in claim 1, wherein the electric stimulation controller outputs multi-channel bipolar pulse constant currents with different frequencies and amplitudes.
6. The electric stimulation driving system for the pressure and joint angle feedback of the artificial finger tip as claimed in claim 1, wherein the electric stimulation controller comprises a power module, a bluetooth module, a controller module, a digital-to-analog conversion module, a voltage-controlled constant current source module, a current polarity conversion module and a current limiting protection module; the controller module, the digital-to-analog conversion module, the voltage-controlled constant current source module, the current polarity conversion module and the current-limiting protection module are all connected with the power supply module, and the controller module is connected with the Bluetooth module;
the power supply module is used for supplying power to each module;
the Bluetooth module is used for receiving the finger pressure and joint angle value of each finger tip;
the controller module is used for generating a control waveform command;
the digital-to-analog conversion module is used for converting a digital signal into an analog signal;
the voltage-controlled constant current source module is used for outputting constant current;
the polarity conversion module is used for controlling the polarity of the output current;
the current-limiting protection module is used for limiting the amplitude of the output current.
7. The electric stimulation driving system for the pressure and joint angle feedback of the artificial finger tip as claimed in claim 6, wherein the electric stimulation controller performs grade division on the obtained pressure and angle values, sets 7 current stimulation grades with stimulation frequencies lower than 100Hz, the current stimulation grades are respectively 1Hz, 2Hz, 4Hz, 8Hz, 16Hz, 32Hz and 64Hz, and the current amplitude is 7 mA.
8. An electrical stimulation driving system for feeding back the pressure of the artificial finger tip and the joint angle according to claim 7, wherein the current stimulation, the division and mapping of the finger joint angle and the finger tip pressure in 7 levels are as follows:
1) the method comprises the following steps of (1) carrying out grade division on angles of the artificial hand, wherein the rotation range of five finger joints of the artificial hand is 0-90 degrees, the artificial hand is divided into three grades, and the angle grade is one in the range of 0-30 degrees; the angle grade is two within the range of 31-60 degrees; the angle grade is three within the range of 61-90 degrees;
2) grading the pressure of the tip of the artificial finger, wherein the pressure grade is 1 in the range of 0-2N; pressure grade 2 in the range of 2-4N; pressure grade 3 in the range of 4-6N; the pressure grade is 4 when the range of 6N is more than the range of 6N;
the seven levels correspond to frequency currents of 1Hz, 2Hz, 4Hz, 8Hz, 16Hz, 32Hz and 64Hz output by the electrical stimulation controller respectively, when the measured pressure and joint angle are positioned at one of the seven levels, the corresponding channel of the electrical stimulation controller is controlled to output the current of the corresponding frequency, the thumb corresponds to the stimulation channel 1, the index finger corresponds to the stimulation channel 2, the middle finger corresponds to the stimulation channel 3, the ring finger corresponds to the stimulation channel 4 and the little finger corresponds to the stimulation channel 5; meanwhile, when the fingertip does not generate pressure, only the finger joint angle is fed back; when the fingertip generates pressure, only the pressure value is fed back; therefore, the user can know various information on the artificial hand to form closed loop feedback.
9. The method for driving the electric stimulation driving system for the pressure and joint angle feedback of the artificial finger tip as claimed in claim 1, which comprises the following steps:
the electrical stimulation controller is provided with 5 stimulation channels, and the channel 1 corresponds to the thumb; the channel 2 corresponds to an index finger; the channel 3 corresponds to a middle finger; the channel 4 corresponds to a ring finger; the channel 5 corresponds to a little finger; when the artificial hand does not grab the object and the pressure value of the fingertip is 0, the electrical stimulation is only directed at the corresponding angle value, and 3 levels of the angle of the artificial finger respectively correspond to the first three stimulation frequencies of the stimulation frequencies; when the artificial hand grabs an article and generates fingertip pressure, the stimulation is only directed at the corresponding fingertip pressure value, and 4 levels of the pressure of the artificial finger tip respectively correspond to the last four stimulation frequencies of the stimulation frequencies; when the pressure or angle value is in a certain level, the electric stimulation controller outputs current with corresponding frequency.
10. The driving method of the electrical stimulation driving system for the pressure and joint angle feedback of the artificial finger tip as claimed in claim 9, wherein after the electrical stimulation controller is powered on, the specific control flow is as follows:
1) enabling a clock;
2) the serial port communication judges whether data is received, if the data is not received, the data is continuously waited, if the data is received, the data enters an interrupt, the received 16-bit data, namely 2 bytes, is stored, and the interrupt is closed;
3) on the basis of the received 16-bit data,
if the value of the lower 4 bits of the 1 st byte is 1, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 1;
if the value of the lower 4 bits of the 1 st byte is 2, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 2;
if the value of the lower 4 bits of the 1 st byte is 3, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 3;
if the value of the lower 4 bits of the 1 st byte is 4, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 4;
if the value of the lower 4 bits of the 1 st byte is 5, the value is a thumb related value and corresponds to the stimulation current parameter of the control channel 5;
4) according to the received 16-bit data, if the value of the first byte is 4 high bits and is 1, the value is a pressure value, the actual pressure value is 8 low bits and is 0.1, according to the mapping relation, the channel is graded, and the channel stimulation current frequency is set; if the high 4-bit numerical value of the first byte is 2, the value is an angle value, the actual angle value is the low 8-bit numerical value of the received data, the levels are divided according to the mapping relation, the stimulation current frequency of the channel is set, and the stimulation current is output;
when the upper limb of the user feels current stimulation, the level of the stimulation frequency and the stimulation channel are judged, the corresponding pressure or angle level is identified according to the mapping relation, and the fingertip pressure and the finger joint angle of the artificial hand are identified.
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