Virtual Reality-Based Remote Knee Joint Rehabilitation Training System

Abstract

The knee joint remote rehabilitation training system based on virtual reality of the present invention. The model parameter waveform acquisition circuit receives the model parameter waveform through high-pass filtering, and outputs it after sampling and holding. The patient's knee joint movement waveform acquisition circuit tracks the phase shift of the model parameter waveform by extracting waveform edges, frequency discrimination by a frequency discriminator, and feedback distortion correction, and outputs it after sampling and holding. The synchronous detection circuit uses a synchronous detector to synchronously detect the clock pulse used as the reference signal and the waveform edge signal. When there is a phase deviation, one path triggers phase shift, and the other path performs controllable delay on the clock pulse, so that the patient's knee joint movement waveform and the model parameter waveform enter the offset tracking circuit synchronously. Under the control of the switch SW1, they enter the integrator for integration and the comparator outputs a square wave to enter the drive compensation circuit in sequence, modulate the model parameter waveform to generate a control pulse through an oscillator, the output square wave modulates the control pulse generated by the oscillator, and finally outputs to the drive module after buffer filtering.

Description

Technical Field

[0001] The present invention belongs to the technical field of rehabilitation training, and particularly relates to a remote rehabilitation training system for knee joints based on virtual reality. Background Art

[0002] Existing knee joint rehabilitation robots can free rehabilitation physicians from heavy rehabilitation treatments. They usually have a power module, a drive module, a robot body, a collection module, and an industrial control computer. The industrial control computer outputs signals to the drive module, and the drive module drives the power device to assist in movement. The collection module collects parameters such as the physiological and functional indicators of the patient, the power and angle of the power module, and feeds them back to the industrial control computer to meet the training requirements. With the development of network remote control technology, rehabilitation physicians can remotely set different rehabilitation modes according to the symptoms of different patients, and can also detect the physiological and functional indicators of patients using various new sensors, providing objective data for rehabilitation physicians to revise training plans. Using human-machine interface technology, patients can also adjust the training intensity and training mode according to their own physical conditions, and can be equipped with VR devices to select the motion scenarios to be simulated, which is conducive to mobilizing the enthusiasm of patients for rehabilitation.

[0003] However, since the rotational training of joints is a non-linear control process, the training intensity often does not match the corresponding mode. Although there is a certain degree of improvement according to the feedback control of the collection module, it is still not possible to perform compliant and impedance control well. Summary of the Invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a remote rehabilitation training system for knee joints based on virtual reality, effectively solving the problem that the prior art cannot perform compliant and impedance control well.

[0005] Its technical solution includes a waveform acquisition circuit, a synchronous demodulation circuit, an offset tracking circuit, and a drive compensation circuit. The waveform acquisition circuit includes a patient knee joint movement waveform acquisition circuit and a model parameter waveform acquisition circuit. The model parameter waveform acquisition circuit receives the model parameter waveform through high-pass filtering, outputs it after sampling and holding. The patient knee joint movement waveform acquisition circuit extracts the waveform edge through an edge detection circuit. The waveform edge is frequency-detected by a frequency discriminator and corrected for feedback distortion, and then outputs a waveform edge without frequency deviation. It enters a phase shift circuit to track the phase shift of the model parameter waveform, and finally outputs it after high-pass filtering and sampling and holding.

[0006] The synchronous detection circuit adopts a synchronous detector composed of an analog switch and a differential amplifier to synchronously detect the clock pulse used as the reference signal and the waveform edge signal. When there is a phase deviation, it is output through a low-pass filter. One path triggers the phase shift circuit in the patient's knee joint movement waveform acquisition circuit to shift the phase, and the other path adds the clock pulse with a controllable delay to the model parameter waveform acquisition circuit, so that the patient's knee joint movement waveform and the model parameter waveform synchronously enter the offset tracking circuit;

[0007] The offset tracking circuit receives the patient's knee joint movement waveform and the model parameter waveform. Under the control of the sampling switch SW1, it successively enters the integrator to integrate and output a triangular wave with a certain rise time and fall time, and then outputs a square wave with a certain duty cycle through a comparator to enter the drive compensation circuit. Among them, the sampling switch SW1 calculates the ratio of the amplitudes of the patient's knee joint movement waveform and the model parameter waveform by a divider, and changes the control of the clock pulse output by the time base chip IC1;

[0008] The drive compensation circuit receives the model parameter waveform after sampling and holding, triggers the oscillator to generate a control pulse, and enters the pin A of the exclusive OR gate U1. The pin B of the exclusive OR gate U1 accesses the square wave with a certain duty cycle output by the comparator. After the exclusive OR operation of the exclusive OR gate U1, the output square wave modulates the control pulse generated by the oscillator, and finally outputs to the drive module after buffering and filtering.

[0009] Advantages of the present invention: 1. The model parameter waveform acquisition circuit uses a high-pass filter to receive the model parameter waveform. After sampling and holding by the sample and hold circuit, it is output as a reference signal. The patient's knee joint movement waveform acquisition circuit extracts the waveform edge through the edge detection circuit. The waveform edge is frequency-discriminated with the frequency of the model parameter waveform by the frequency discriminator. The non-zero voltage of the non-harmonic frequency is fed back to the negative electrode of the varactor diode DC2 through the diode D1. After further frequency modulation and frequency distortion correction, a waveform edge without frequency deviation is output and enters the phase shift circuit to track the phase shift of the model parameter waveform. Finally, after high-pass filtering and sampling and holding, it is output. Under the control of the sampling switch SW1, the instantaneous point signals of the patient's knee joint movement waveform and the model parameter waveform enter the integrator successively to integrate and output a triangular wave with a certain rise time and fall time. If the amplitudes of the instantaneous point signals are equal and the rise time and fall time are equal, then after comparison with the reference voltage REF by the comparator, a symmetric square wave with a 50% duty cycle is output. Otherwise, a square wave with a certain duty cycle is output for each instantaneous point. Among them, the sampling switch SW1 calculates the ratio of the amplitudes of the synchronized patient's knee joint movement waveform and the model parameter waveform by the divider IC2 and is controlled by changing the clock pulse output by the time base chip IC1. Thus, the offset of each instantaneous point is tracked and compared, and a compensation amount is output. Also, according to the roughly estimated amplitude ratio, the clock pulse of the sampling switch SW1 can be changed, that is, the frequency of instantaneous point acquisition under one clock pulse is changed, so as to achieve non-linear control, which is beneficial for compliant and impedance control;

[0010] 2. A synchronous detector composed of the analog switch IC3 and the differential amplifier AR3 is used to synchronously detect the clock pulse and the waveform edge signal used as the reference signal. When there is a phase deviation, it is output through the low-pass filter. One path triggers the phase shift circuit to shift the phase, and the other path adds the clock pulse with controllable delay to the model parameter waveform acquisition circuit, so that the patient's knee joint movement waveform and the model parameter waveform enter the offset tracking circuit synchronously, and precise synchronous control can be achieved;

[0011] 3. The drive compensation circuit receives the model parameter waveform after sampling and holding, triggers the oscillator to generate corresponding control pulses, and enters the pin A of the exclusive-OR gate U1. The pin B of the exclusive-OR gate U1 is connected to the comparator to output a square wave with a certain duty cycle. Through the exclusive-OR operation of the exclusive-OR gate U1, the control pulse generated by the oscillator is modulated by the output square wave, and finally, after buffering and filtering, it is output to the drive module. Thus, non-linear compensation is performed to make the training intensity adapt to the corresponding mode and is beneficial for compliant and impedance control. Brief Description of the Drawings

[0012] Figure 1 is the schematic diagram of the model parameter waveform acquisition circuit of the present invention.

[0013] Figure 2 is the schematic diagram of the patient's knee joint movement waveform acquisition circuit of the present invention.

[0014] Figure 3 This is the schematic diagram of the synchronous detection circuit of the present invention.

[0015] Figure 4 This is the schematic diagram of the offset tracking circuit of the invention.

[0016] Figure 5 This is the schematic diagram of the drive compensation circuit of the invention.

[0017] Figure 6 This is the overall block diagram of the invention. Specific Embodiments

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0019] The following will be combined with the attached Figures 1 to 6 description of the specification to further elaborate on the specific embodiments of the present invention.

[0020] A virtual reality-based remote knee rehabilitation training system includes a waveform acquisition circuit, a synchronous detection circuit, an offset tracking circuit, and a drive compensation circuit. The waveform acquisition circuit includes a patient knee joint movement waveform acquisition circuit and a model parameter waveform acquisition circuit. The model parameter waveform acquisition circuit receives the model parameter waveform through high-pass filtering, and outputs it after sample and hold. Among them, the frequency of sample and hold is controlled by the clock pulse applied to the gate of field effect transistor T1 after delay. The patient knee joint movement waveform acquisition circuit extracts the waveform edge through an edge detection circuit. The waveform edge is frequency discriminated with the frequency of the model parameter waveform through a frequency discriminator. The non-zero voltage of the non-harmonic frequency is fed back to the negative electrode of varactor diode DC2 through diode D1, and is further frequency modulated through crystal oscillator X1, varactor diode DC2, and capacitor C8. After frequency distortion correction, a waveform edge without frequency deviation is output, enters a phase shift circuit composed of a transformer to track the phase shift of the model parameter waveform, and finally is output after high-pass filtering and sample and hold by a sample and hold circuit. Among them, the frequency of sample and hold is controlled by the clock pulse applied to the gate of field effect transistor T2. The synchronous detection circuit receives the clock pulse output by the industrial control computer, and uses a synchronous detector composed of analog switch IC3 and differential amplifier AR3 to synchronously detect the clock pulse used as the reference signal and the waveform edge signal. When there is a phase deviation, it is output through a low-pass filter. One way triggers the phase shift of the phase shift circuit in the patient knee joint movement waveform acquisition circuit, and the other way adds the clock pulse with controllable delay to the model parameter waveform acquisition circuit, so that the patient knee joint movement waveform and the model parameter waveform enter the offset tracking circuit synchronously. The offset tracking circuit receives the patient knee joint movement waveform and the model parameter waveform. Under the control of sampling switch SW1, the instantaneous point signals of the patient knee joint movement waveform and the model parameter waveform enter the integrator successively to integrate and output a triangular wave with a certain rise time and fall time. If the amplitudes of the instantaneous point signals are equal and the rise time and fall time are equal, then it is compared with the reference voltage REF through a comparator, and a symmetric square wave with a 50% duty cycle is output. Otherwise, a square wave with a certain duty cycle is output for each instantaneous point and enters the drive compensation circuit. Among them, sampling switch SW1 is calculated by divider IC2 to obtain the ratio of the amplitude of the synchronous patient knee joint movement waveform and the model parameter waveform, and is controlled by changing the clock pulse output by time base chip IC1. Thus, the offset of each instantaneous point is tracked and compared, and a compensation amount is output, and the clock pulse of sampling switch SW1 can be changed according to the roughly estimated amplitude ratio, that is, the frequency of instantaneous point acquisition under one clock pulse is changed, so as to achieve non-linear control, which is beneficial for compliant and impedance control. The drive compensation circuit receives the model parameter waveform after sample and hold, triggers an oscillator to generate a corresponding control pulse, enters pin A of exclusive OR gate U1, and pin B of exclusive OR gate U1 is connected to the comparator to output a square wave with a certain duty cycle. The exclusive OR operation of exclusive OR gate U1 modulates the control pulse generated by the oscillator, and finally outputs it to the drive module after buffering and filtering, thus realizing non-linear compensation.Adapt the training intensity to the corresponding mode, which is conducive to compliant and impedance control.

[0021] In the above technical solution, the model parameter waveform acquisition circuit uses a high-pass filter composed of capacitor C1 and resistor R4 to receive the model parameter waveform (that is, the gait cycle waveform data that should be generated when the output signal of the industrial control computer is sent to the drive module and the power device for auxiliary movement in different modes). After being sampled and held by the sample and hold circuit composed of field effect transistor T1, capacitor C2, and operational amplifier AR5, it is output as a reference signal. Among them, the sampling and holding frequency is controlled by the clock pulse applied to the gate of field effect transistor T1 through the series delay of resistor R3A, capacitor C4, and varactor diode DC1. It includes capacitor C1. One end of capacitor C1 is connected to the model parameter waveform, and the other end of capacitor C1 is respectively connected to one end of the grounded resistor R4 and the drain of field effect transistor T1. The source of field effect transistor T1 is respectively connected to one end of the grounded capacitor C2 and the non-inverting input terminal of operational amplifier AR5. The gate of field effect transistor T1 is respectively connected to one end of resistor R3A and one end of capacitor C4. The other end of capacitor C4 is respectively connected to the negative electrode of varactor diode DC1 and the output terminal of operational amplifier AR4. The positive electrode of varactor diode DC1 is grounded. The other end of resistor R3A is connected to pin 2 of NOT gate U2. The inverting input terminal and the output terminal of operational amplifier AR5 are the output terminals of the model parameter waveform acquisition circuit.

[0022] In the above technical solution, the waveform acquisition circuit for the patient's knee joint movement extracts waveform edges through an edge detection circuit composed of electrolytic capacitors E1 and E2, resistors R1 and R2, and operational amplifier AR1 (the waveform of the patient's knee joint movement can be obtained by a camera collecting gait image data of the patient's knee joint movement, and obtaining a video sequence of the gait through detection and tracking,It is obtained by extracting the gait activity waveform features of this person through preprocessing analysis. It can also be obtained by collecting the physiological and functional indicators of the patient, the power and angle parameters of the power module by the acquisition module, and establishing module parameters. This is the prior art and will not be elaborated here. The waveform edge is frequency-discriminated with the model parameter waveform frequency by a frequency discriminator composed of capacitors C5 and C6, transformer T2, and crystal oscillator X1. The non-zero voltage of the non-harmonic frequency is fed back to the negative electrode of varactor diode DC2 through diode D1, and further frequency-modulated through crystal oscillator X1, varactor diode DC2, and capacitor C8. After frequency distortion correction, a waveform edge without frequency deviation is output and enters a phase-shifting circuit composed of a transformer formed by capacitors C8 - C10, inductor L4, and inductor L5 to track the phase shift of the model parameter waveform. Finally, it is high-pass filtered by capacitor C11 and resistor R16, and sampled and held by a sample-and-hold circuit composed of field-effect transistor T2, capacitor C60, and operational amplifier AR2 and then output. Among them, the sampling and holding frequency is controlled by the clock pulse applied to the gate of field-effect transistor T2, including electrolytic capacitors E1 and E2, capacitor C5, and transformer T2. The negative electrode of electrolytic capacitor E1, the negative electrode of electrolytic capacitor E2, the lower end of capacitor C5, and one end of the primary coil of transformer T2 are connected to the knee joint activity waveform. The positive electrode of electrolytic capacitor E1 is respectively connected to one end of grounding resistor R1 and the non-inverting input terminal of operational amplifier AR1. The positive electrode of electrolytic capacitor E2 is respectively connected to one end of grounding resistor R2 and the inverting input terminal of operational amplifier AR1. The output terminal of operational amplifier AR1 is connected to the upper end of capacitor C5 and the other end of the primary coil of transformer T2. One end of the secondary coil of transformer T2 is connected to one end of capacitor C6. The other end of capacitor C6 is respectively connected to the upper end of crystal oscillator X1, the positive electrode of diode D1, and one end of capacitor C20. The negative electrode of diode D1 is respectively connected to one end of resistor R14, one end of capacitor C7, and one end of resistor R15. The other end of resistor R15 is connected to the negative electrode of varactor diode DC2 and the left end of crystal oscillator X2. The other end of the secondary coil of transformer T2 is respectively connected to the lower end of crystal oscillator X1, the other end of resistor R14, and the other end of capacitor C7. The positive electrode of varactor diode DC2 is grounded. The right end of crystal oscillator X2 is respectively connected to one end of grounding capacitor C8, one end of grounding inductor L4, one end of capacitor C9, and the other end of capacitor C20. The other end of capacitor C9 is respectively connected to one end of grounding inductor L5, one end of grounding capacitor C10, and one end of capacitor C11. The other end of capacitor C11 is respectively connected to one end of grounding resistor R16 and the drain of field-effect transistor T2. The gate of field-effect transistor T2 is connected to pin 1 of NOT gate U2. The source of field-effect transistor T2 is respectively connected to one end of grounding capacitor C60 and the inverting input terminal of operational amplifier AR2. The non-inverting input terminal and the output terminal of operational amplifier AR2 are the output terminals of the patient knee joint activity waveform acquisition circuit.,

[0023] In the above technical solution, the synchronous detection circuit receives the clock pulses output by the industrial control computer, and after being inverted by the NOT gate, they are added to pins 3 and 10 of the analog switch IC3. The received waveform edge signal is added to pin 13 of the analog switch IC3 (which can be AD7512) through the capacitor C3. A synchronous detector composed of the analog switch IC3 and the differential amplifier AR3 is used to synchronously detect the clock pulses and the waveform edge signal used as the reference signal. When there is a phase deviation, it is output through the low-pass filter composed of the resistors R12 and R13, the capacitors C13 and C14, and the operational amplifier AR4. One path triggers the phase shift circuit in the patient's knee joint movement waveform acquisition circuit to shift the phase, and the other path adds the clock pulses with controllable delay to the model parameter waveform acquisition circuit, so that the patient's knee joint movement waveform and the model parameter waveform synchronously enter the offset tracking circuit, including the NOT gate U2. The pin 1 of the NOT gate U2 is connected to the clock pulses, the pin 2 of the NOT gate U2 is connected to one end of the resistor R3, and the other end of the resistor R3 is respectively connected to pins 3 and 10 of the chip IC3. The pins 2 and 4 of the chip IC3 are connected to the ground, the pins 1 and 7 of the chip IC3 are connected to the power supply +5V, the pin 13 of the chip IC3 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to the output end of the operational amplifier AR1. The pins 9 and 14 of the chip IC3 are connected to one end of the resistor R8, and the other end of the resistor R8 is respectively connected to the non-inverting input terminal of the operational amplifier AR3 and one end of the resistor R11. The pins 11 and 12 of the chip IC3 are connected to one end of the resistor R9, and the other end of the resistor R9 is respectively connected to the inverting input terminal of the operational amplifier AR3 and one end of the grounding resistor R10. The output end of the operational amplifier AR3 is respectively connected to the other end of the resistor R11 and one end of the resistor R12. The other end of the resistor R12 is respectively connected to one end of the resistor R13 and one end of the capacitor C13. The other end of the resistor R13 is respectively connected to one end of the grounding capacitor C14, the non-inverting input terminal and the inverting input terminal of the operational amplifier AR4. The output end of the operational amplifier AR4 and the other end of the capacitor C13 are the output terminals of the synchronous detection circuit.

[0024] In the above technical solution, the offset tracking circuit receives the waveforms of the patient's knee joint movement and the model parameter waveforms. Under the control of the sampling switch SW1, the instantaneous point signals of the waveforms of the patient's knee joint movement and the model parameter waveforms enter the integrator in sequence to integrally output a triangular wave with a certain rise time and fall time. If the amplitudes of the instantaneous point signals are equal and the rise time and fall time are equal, then after being compared with the reference voltage REF by the comparator, a symmetric square wave with a 50% duty cycle is output. Otherwise, a square wave with a certain duty cycle is output for each instantaneous point and enters the drive compensation circuit. Among them, the sampling switch SW1 calculates the ratio of the amplitudes of the synchronized waveforms of the patient's knee joint movement and the model parameter waveforms by the divider IC2 (the amplitude of the waveform of the patient's knee joint movement is obtained by detecting the peak value by the peak detection circuit composed of the electrolytic capacitor E3, diodes D2 and D3, inductor L2 and capacitor C12, and the amplitude of the model parameter waveform is obtained by detecting the peak value by the peak detection circuit composed of the electrolytic capacitor E4, diodes D4 and D5, inductor H2 and capacitor C7). It is controlled by changing the clock pulse output by the time base chip IC1. The input of the time base chip IC1 is a clock pulse, and usually the output is set to a clock pulse with a frequency doubling. When the ratio of the amplitudes is high, the voltage regulator diode Z1 breaks down, changing the charge and discharge time of the time base chip IC1 and further changing the output clock pulse. Thus, the offset of each instantaneous point is tracked and compared, and the compensation amount is output. And the clock pulse of the sampling switch SW1 can be changed according to the roughly estimated ratio of the amplitudes, that is, the frequency of instantaneous point acquisition under one clock pulse is changed, so as to achieve non-linear control, which is beneficial to compliance and impedance control. It includes the switch SW1, the electrolytic capacitor E4, and the electrolytic capacitor E3. The normally closed contact of the switch SW1 is connected to the output terminal of the operational amplifier AR5 through the resistor R5. The normally open contact of the switch SW1 is connected to the output terminal of the operational amplifier AR2 through the resistor R5A. The common contact of the switch SW1 is connected to one end of the resistor R6. The other end of the resistor R6 is respectively connected to one end of the capacitor C5 and the inverting input terminal of the operational amplifier AR6. The non-inverting input terminal of the operational amplifier AR6 is connected to the ground. The output terminal of the operational amplifier AR6 is respectively connected to the other end of the capacitor C5 and one end of the resistor R19. The other end of the resistor R19 is respectively connected to one end of the grounding resistor R20, one end of the resistor R21, and the non-inverting input terminal of the operational amplifier AR7. The inverting input terminal of the operational amplifier AR7 is connected to the REF reference signal. The output terminal of the operational amplifier AR7 is respectively connected to the other end of the resistor R21 and one end of the resistor R7. The other end of the resistor R7 and one end of the grounding capacitor C6 are the output signals of the offset tracking circuit. The negative electrode of the electrolytic capacitor E4 is connected to the normally closed contact of the switch SW1. The positive electrode of the electrolytic capacitor E4 is respectively connected to the negative electrode of the diode D4 and the positive electrode of the diode D5. The positive electrode of the diode D4 is connected to the ground. The negative electrode of the diode D5 is connected to one end of the inductor H1. The other end of the inductor H1 is respectively connected to one end of the grounding capacitor C7 and the pin 6 of the multiplier IC2.The negative electrode of the electrolytic capacitor E3 is connected to the normally open contact of the switch SW1. The positive electrode of the electrolytic capacitor E3 is respectively connected to the negative electrode of the diode D2 and the positive electrode of the diode D3. The positive electrode of the diode D2 is connected to the ground. The negative electrode of the diode D3 is connected to one end of the inductor H2. The other end of the inductor H2 is respectively connected to one end of the grounded capacitor C12 and the pin 1 of the multiplier IC2. The pins 7, 8, 9, and 10 of the multiplier IC2 are connected to the ground. The pin 2 of the multiplier IC2 is connected to the power supply +15V. The pin 5 of the multiplier IC2 is connected to the power supply -15V. The pin 3 of the multiplier IC2 is connected to the middle terminal of the potentiometer RP1. The lower end of the potentiometer RP1 is connected to the ground. The pin 4 of the multiplier IC2 is respectively connected to the upper end of the potentiometer RP1 and one end of the resistor R17. The other end of the resistor R17 is connected to the negative electrode of the zener diode Z1. The positive electrode of the zener diode Z1 is respectively connected to the negative electrode of the varactor diode DC3 and one end of the grounded capacitor C10. The positive electrode of the varactor diode DC3 is respectively connected to the pins 6 and 7 of the timer chip IC1 and one end of the resistor R18. The pins 4 and 8 of the timer chip IC1 and the other end of the resistor R18 are connected to the power supply +5V. The pin 2 of the timer chip IC1 is respectively connected to the positive electrode of the diode D6 and one end of the capacitor C9. The other end of the capacitor C9 is connected to the clock pulse. The negative electrode of the diode D6 is connected to the power supply +5V. The pin 3 of the timer chip IC1 is connected to the control terminal of the switch SW1.

[0025] In the above technical solution, the drive compensation circuit receives the sampled and held model parameter waveform, triggers the oscillator composed of chip IC3, resistor R26, capacitor C15 and capacitor C16 to generate corresponding control pulses, which enter pin A of exclusive-OR gate U1. The output of a square wave with a certain duty cycle from the comparator is connected to pin B of exclusive-OR gate U1. After the exclusive-OR operation of exclusive-OR gate U1, the output square wave enters the modulation circuit composed of operational amplifier AR8, resistors R22, R23, R27, R28 and zener diode Z2 to modulate the control pulses generated by the oscillator. Finally, after buffering and filtering, it is output to the drive module. Through this non-linear compensation, the training intensity is adapted to the corresponding mode, which is beneficial for compliant and impedance control. The circuit includes exclusive-OR gate U1 and chip IC3. One end of resistor R26 is connected to pin 6 of chip IC3, and one end of grounded capacitor C15 is connected to pin 7 of chip IC3. The other end of resistor R7 is connected to pin 2 of chip IC3. Pins 4 and 8 of chip IC3 are connected to the power supply +5V. One end of grounded capacitor C16 is connected to pin 5 of chip IC3. Pin 1 of chip IC3 is grounded. Pin 3 of chip IC3 is respectively connected to one end of resistor R23 and pin A of exclusive-OR gate U1. The other end of resistor R23 is respectively connected to the non-inverting input terminal of operational amplifier AR8 and one end of resistor R22. The inverting input terminal of operational amplifier AR8 is respectively connected to one end of resistor R27, one end of resistor R28 and one end of grounded capacitor C18. The other end of resistor R27 is connected to pin Y of exclusive-OR gate U1. Pin B of exclusive-OR gate U1 is connected to the other end of resistor R7. The other end of resistor R28 is respectively connected to the other end of resistor R22, the positive electrode of zener diode Z2 and the emitter of triode Q1. The negative electrode of zener diode Z2 is connected to the output terminal of operational amplifier AR8. The base of triode Q1 and one end of resistor R25 are connected to the power supply +5V. The collector of triode Q1 is respectively connected to the other end of resistor R25 and one end of resistor R24. The other end of resistor R24 and one end of grounded capacitor C17 are jointly connected to the output to the drive module.

[0026] When the present invention is specifically used, the model parameter waveform acquisition circuit uses a high-pass filter to receive the model parameter waveform. After being sampled and held by a sample-and-hold circuit, it is output as a reference signal. Among them, the sampling and holding frequency is controlled by the clock pulse applied to the gate of field effect transistor T1 after being delayed. The patient's knee joint movement waveform acquisition circuit extracts the waveform edge through an edge detection circuit. The waveform edge is frequency-discriminated with the frequency of the model parameter waveform by a frequency discriminator. The non-zero voltage of the non-harmonic frequency is fed back to the negative electrode of varactor diode DC2 through diode D1, and further frequency-modulated through crystal oscillator X1, varactor diode DC2, and capacitor C8. After frequency distortion correction, a waveform edge without frequency deviation is output, enters a phase shift circuit composed of a transformer to track the phase shift of the model parameter waveform, and finally is output after high-pass filtering and being sampled and held by a sample-and-hold circuit. Among them, the sampling and holding frequency is controlled by the clock pulse applied to the gate of field effect transistor T2. The synchronous detection circuit receives the clock pulse output by the industrial control computer, adds it to pins 3 and 10 of analog switch IC3 through an inverter, and receives the waveform edge signal and adds it to pin 13 of analog switch IC3 through capacitor C3. A synchronous detector composed of analog switch IC3 and differential amplifier AR3 is used to synchronously detect the clock pulse used as the reference signal and the waveform edge signal. When there is a phase deviation, it is output through a low-pass filter. One way triggers the phase shift of the phase shift circuit in the patient's knee joint movement waveform acquisition circuit, and the other way adds the clock pulse with controllable delay to the model parameter waveform acquisition circuit, so that the patient's knee joint movement waveform and the model parameter waveform synchronously enter the offset tracking circuit. The offset tracking circuit receives the patient's knee joint movement waveform and the model parameter waveform. Under the control of sampling switch SW1, the instantaneous point signals of the patient's knee joint movement waveform and the model parameter waveform enter the integrator successively for integration and output a triangular wave with a certain rise time and fall time. If the amplitudes of the instantaneous point signals are equal and the rise time and fall time are equal, then it is compared with the reference voltage REF by a comparator and a symmetric square wave with a 50% duty cycle is output. Otherwise, a square wave with a certain duty cycle is output for each instantaneous point and enters the drive compensation circuit. Among them, sampling switch SW1 calculates the ratio of the amplitudes of the synchronous patient's knee joint movement waveform and the model parameter waveform by divider IC2, and is controlled by changing the clock pulse output by time base chip IC1. The input of time base chip IC1 is the clock pulse, and usually the output is a clock pulse with a double frequency. When the amplitude ratio is high, zener diode Z1 breaks down, changing the charge and discharge time of time base chip IC1 and further changing the output clock pulse. Thus, the offset of each instantaneous point is tracked and compared, and a compensation amount is output, and the clock pulse of sampling switch SW1 can be changed according to the roughly estimated amplitude ratio, that is, the frequency of instantaneous point acquisition under one clock pulse is changed, so as to achieve non-linear control, which is beneficial for compliant and impedance control. The drive compensation circuit receives the model parameter waveform after sampling and holding, triggers an oscillator to generate corresponding control pulses, and enters pin A of exclusive OR gate U1.The pin B of the XOR gate U1 is connected to the square wave with a certain duty cycle output by the comparator. After XOR operation by the XOR gate U1, the output square wave modulates the control pulse generated by the oscillator. Finally, it is output to the drive module after buffering and filtering. Thus, non-linear compensation is achieved, making the training intensity adapt to the corresponding mode and facilitating compliant and impedance control.

Claims

1. A virtual reality-based remote rehabilitation training system for knee joints, comprising a waveform acquisition circuit, a synchronous detection circuit, an offset tracking circuit, and a drive compensation circuit. Characterized in that, The waveform acquisition circuit includes a patient knee joint movement waveform acquisition circuit and a model parameter waveform acquisition circuit. The model parameter waveform acquisition circuit receives the model parameter waveform through high-pass filtering, outputs it after sampling and holding. The patient knee joint movement waveform acquisition circuit extracts the waveform edge through an edge detection circuit. The waveform edge is frequency-detected by a frequency discriminator and corrected for feedback distortion, and then outputs a waveform edge without frequency deviation, which enters a phase shift circuit to track the phase shift of the model parameter waveform, and finally outputs after high-pass filtering and sampling and holding. The synchronous detection circuit uses a synchronous detector composed of an analog switch and a differential amplifier to synchronously detect the clock pulse used as a reference signal and the waveform edge signal. When there is a phase deviation, it outputs through a low-pass filter. One path triggers the phase shift circuit in the patient knee joint movement waveform acquisition circuit to shift the phase, and the other path adds the clock pulse with controllable delay to the model parameter waveform acquisition circuit, so that the patient knee joint movement waveform and the model parameter waveform synchronously enter the offset tracking circuit. The offset tracking circuit receives the patient knee joint movement waveform and the model parameter waveform. Under the control of the sampling switch SW1, it successively enters an integrator to integrate and output a triangular wave with a certain rise time and fall time, and then outputs a square wave with a certain duty cycle through a comparator to enter the drive compensation circuit. Among them, the sampling switch SW1 is controlled by calculating the ratio of the amplitudes of the patient knee joint movement waveform and the model parameter waveform by a divider and changing the clock pulse output by the time base chip IC1. The drive compensation circuit receives the model parameter waveform after sampling and holding, triggers an oscillator to generate a control pulse, which enters pin A of the exclusive OR gate U1. Pin B of the exclusive OR gate U1 is connected to the square wave output by the comparator with a certain duty cycle. The exclusive OR operation of the exclusive OR gate U1 modulates the control pulse generated by the oscillator, and finally outputs it to the drive module after buffering and filtering.

2. The virtual reality-based remote rehabilitation training system for knee joints according to claim 1, Characterized in that, The model parameter waveform acquisition circuit includes a capacitor C1. One end of the capacitor C1 is connected to the model parameter waveform. The other end of the capacitor C1 is respectively connected to one end of a grounding resistor R4 and the drain of a field effect transistor T1. The source of the field effect transistor T1 is respectively connected to one end of a grounding capacitor C2 and the non-inverting input terminal of an operational amplifier AR5. The gate of the field effect transistor T1 is respectively connected to one end of a resistor R3A and one end of a capacitor C4. The other end of the capacitor C4 is respectively connected to the negative electrode of a varactor diode DC1 and the output terminal of an operational amplifier AR4. The positive electrode of the varactor diode DC1 is grounded. The other end of the resistor R3A is connected to pin 2 of a NOT gate U2. The inverting input terminal and the output terminal of the operational amplifier AR5 are the output terminals of the model parameter waveform acquisition circuit.

3. The virtual reality-based remote rehabilitation training system for knee joints according to claim 1, Characterized in that, The knee joint movement waveform acquisition circuit of the patient includes electrolytic capacitors E1 and E2, capacitor C5, and transformer T2. The negative electrodes of electrolytic capacitor E1 and electrolytic capacitor E2, the lower end of capacitor C5, and one end of the primary coil of transformer T2 are connected to the knee joint movement waveform. The positive electrode of electrolytic capacitor E1 is respectively connected to one end of grounding resistor R1 and the non-inverting input terminal of operational amplifier AR1. The positive electrode of electrolytic capacitor E2 is respectively connected to one end of grounding resistor R2 and the inverting input terminal of operational amplifier AR1. The output terminal of operational amplifier AR1 is connected to the upper end of capacitor C5 and the other end of the primary coil of transformer T2. One end of the secondary coil of transformer T2 is connected to one end of capacitor C6. The other end of capacitor C6 is respectively connected to the upper end of crystal oscillator X1, the positive electrode of diode D1, and one end of capacitor C20. The negative electrode of diode D1 is respectively connected to one end of resistor R14, one end of capacitor C7, and one end of resistor R15. The other end of resistor R15 is connected to the negative electrode of varactor diode DC2 and the left end of crystal oscillator X2. The other end of the secondary coil of transformer T2 is respectively connected to the lower end of crystal oscillator X1, the other end of resistor R14, and the other end of capacitor C7. The positive electrode of varactor diode DC2 is grounded. The right end of crystal oscillator X2 is respectively connected to one end of grounding capacitor C8, one end of grounding inductor L4, one end of capacitor C9, and the other end of capacitor C20. The other end of capacitor C9 is respectively connected to one end of grounding inductor L5, one end of grounding capacitor C10, and one end of capacitor C11. The other end of capacitor C11 is respectively connected to one end of grounding resistor R16 and the drain of field effect transistor T2. The gate of field effect transistor T2 is connected to pin 1 of NOT gate U2. The source of field effect transistor T2 is respectively connected to one end of grounding capacitor C60 and the inverting input terminal of operational amplifier AR2. The non-inverting input terminal and the output terminal of operational amplifier AR2 are the output terminals of the knee joint movement waveform acquisition circuit of the patient.

4. The virtual reality-based remote knee joint rehabilitation training system according to claim 1, characterized in that The synchronous detection circuit includes a NOT gate U2. The pin 1 of the NOT gate U2 is connected to a clock pulse. The pin 2 of the NOT gate U2 is connected to one end of a resistor R3. The other end of the resistor R3 is respectively connected to the pin 3 and the pin 10 of a chip IC3. The pin 2 and the pin 4 of the chip IC3 are connected to ground. The pin 1 and the pin 7 of the chip IC3 are connected to a power supply +5V. The pin 13 of the chip IC3 is connected to one end of a capacitor C3. The other end of the capacitor C3 is connected to the output end of an operational amplifier AR1. The pin 9 and the pin 14 of the chip IC3 are connected to one end of a resistor R8. The other end of the resistor R8 is respectively connected to the non-inverting input end of an operational amplifier AR3 and one end of a resistor R11. The pin 11 and the pin 12 of the chip IC3 are connected to one end of a resistor R9. The other end of the resistor R9 is respectively connected to the inverting input end of the operational amplifier AR3 and one end of a grounding resistor R10. The output end of the operational amplifier AR3 is respectively connected to the other end of the resistor R11 and one end of a resistor R12. The other end of the resistor R12 is respectively connected to one end of a resistor R13 and one end of a capacitor C13. The other end of the resistor R13 is respectively connected to one end of a grounding capacitor C14, the non-inverting input end and the inverting input end of an operational amplifier AR4. The output end of the operational amplifier AR4 and the other end of the capacitor C13 are the output ends of the synchronous detection circuit.

5. The virtual reality-based remote knee joint rehabilitation training system according to claim 1, characterized in that The offset tracking circuit includes a switch SW1, an electrolytic capacitor E4, and an electrolytic capacitor E3. The normally closed contact of the switch SW1 is connected to the output terminal of an operational amplifier AR5 through a resistor R5. The normally open contact of the switch SW1 is connected to the output terminal of an operational amplifier AR2 through a resistor R5A. The common contact of the switch SW1 is connected to one end of a resistor R6. The other end of the resistor R6 is respectively connected to one end of a capacitor C5 and the inverting input terminal of an operational amplifier AR6. The non-inverting input terminal of the operational amplifier AR6 is connected to ground. The output terminal of the operational amplifier AR6 is respectively connected to the other end of the capacitor C5 and one end of a resistor R19. The other end of the resistor R19 is respectively connected to one end of a grounding resistor R20, one end of a resistor R21, and the non-inverting input terminal of an operational amplifier AR7. The inverting input terminal of the operational amplifier AR7 is connected to a REF reference signal. The output terminal of the operational amplifier AR7 is respectively connected to the other end of the resistor R21 and one end of a resistor R7. The other end of the resistor R7 and one end of a grounding capacitor C6 are the output signals of the offset tracking circuit. The negative electrode of the electrolytic capacitor E4 is connected to the normally closed contact of the switch SW1. The positive electrode of the electrolytic capacitor E4 is respectively connected to the negative electrode of a diode D4 and the positive electrode of a diode D5. The positive electrode of the diode D4 is connected to ground. The negative electrode of the diode D5 is connected to one end of an inductor H1. The other end of the inductor H1 is respectively connected to one end of a grounding capacitor C7 and pin 6 of a multiplier IC2. The negative electrode of the electrolytic capacitor E3 is connected to the normally open contact of the switch SW1. The positive electrode of the electrolytic capacitor E3 is respectively connected to the negative electrode of a diode D2 and the positive electrode of a diode D3. The positive electrode of the diode D2 is connected to ground. The negative electrode of the diode D3 is connected to one end of an inductor H2. The other end of the inductor H2 is respectively connected to one end of a grounding capacitor C12 and pin 1 of the multiplier IC2. Pins 7, 8, 9, and 10 of the multiplier IC2 are connected to ground. Pin 2 of the multiplier IC2 is connected to a power supply +15V. Pin 5 of the multiplier IC2 is connected to a power supply -15V. Pin 3 of the multiplier IC2 is connected to the middle terminal of a potentiometer RP1. The lower end of the potentiometer RP1 is connected to ground. Pin 4 of the multiplier IC2 is respectively connected to the upper end of the potentiometer RP1 and one end of a resistor R17. The other end of the resistor R17 is connected to the negative electrode of a zener diode Z1. The positive electrode of the zener diode Z1 is respectively connected to the negative electrode of a varactor diode DC3 and one end of a grounding capacitor C10. The positive electrode of the varactor diode DC3 is respectively connected to pins 6 and 7 of a time base chip IC1 and one end of a resistor R18. Pins 4 and 8 of the time base chip IC1 and the other end of the resistor R18 are connected to a power supply +5V. Pin 2 of the time base chip IC1 is respectively connected to the positive electrode of a diode D6 and one end of a capacitor C9. The other end of the capacitor C9 is connected to a clock pulse. The negative electrode of the diode D6 is connected to a power supply +5V. Pin 3 of the time base chip IC1 is connected to the control terminal of the switch SW1.

6. The virtual reality-based knee joint remote rehabilitation training system according to claim 1, characterized in that The driving compensation circuit includes an exclusive-OR gate U1 and a chip IC3. One end of a resistor R26 and one end of a grounding capacitor C15 are respectively connected to pin 6 and pin 7 of the chip IC3. The other end of a resistor R7 is connected to pin 2 of the chip IC3. Pins 4 and 8 of the chip IC3 are connected to the power supply +5V. One end of a grounding capacitor C16 is connected to pin 5 of the chip IC3. Pin 1 of the chip IC3 is connected to ground. One end of a resistor R23 and pin A of the exclusive-OR gate U1 are respectively connected to pin 3 of the chip IC3. The other end of the resistor R23 is respectively connected to the non-inverting input terminal of an operational amplifier AR8 and one end of a resistor R22. The inverting input terminal of the operational amplifier AR8 is respectively connected to one end of a resistor R27, one end of a resistor R28, and one end of a grounding capacitor C18. The other end of the resistor R27 is connected to pin Y of the exclusive-OR gate U1. Pin B of the exclusive-OR gate U1 is connected to the other end of the resistor R7. The other end of the resistor R28 is respectively connected to the other end of the resistor R22, the positive electrode of a voltage stabilizing diode Z2, and the emitter of a triode Q1. The negative electrode of the voltage stabilizing diode Z2 is connected to the output terminal of the operational amplifier AR8. The base of the triode Q1 and one end of a resistor R25 are connected to the power supply +5V. The collector of the triode Q1 is respectively connected to the other end of the resistor R25 and one end of a resistor R24. The other end of the resistor R24 and one end of a grounding capacitor C17 are commonly connected to the output to the driving module.

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