CN114305996B - Speed control system and method for lower limb robot - Google Patents

Abstract

The invention provides a speed control system and a method for a lower limb robot, which comprises the following steps: laser doppler sensor module: the device is fixed on a lower limb robot, emits laser to the ground, and acquires the Doppler signal generated in the movement process by collecting the scattered light on the ground; the signal processing module: measuring and calculating characteristic frequency in the Doppler signal so as to measure the speed in the motion process; a speed adjusting module: regulating the next movement speed of the lower limb robot in real time according to the measured data; the structural part: the laser Doppler sensor module, the signal processing module and the speed adjusting module are fixed on the lower limb robot through structural parts. The laser Doppler sensor is innovatively applied to a wearable robot speed measuring system, the sensor is high in precision and spatial resolution, cannot be influenced by motion vibration during working, and is stable in light path, good in light source thermal stability, long in service life and suitable for long-time working.

Description

Lower limb robot speed control system and method

technical field

The invention relates to the control field of lower limb rehabilitation robots, in particular to a lower limb robot speed control system and method.

Background technique

Due to diseases and safety accidents, the number of patients with walking dysfunction has been increasing. Due to the backward medical level and high medical expenses in some areas, many patients have missed the best opportunity for rehabilitation. It is particularly urgent to develop lower limb rehabilitation robots to restore walking ability at home without having to bear high medical expenses.

Traditional lower limb rehabilitation training robots rarely have speed adjustment functions. When using lower limb robots for rehabilitation training, the speed and pace of the walking process cannot be controlled. The speed is too slow to achieve the effect of rehabilitation training. Existing lower-limb robots with speed adjustment systems use pattern recognition technology to collect motion information, but this method is difficult to implement and requires high research and development costs. Therefore, a lower-limb robot speed adjustment system with low cost and technical difficulty can provide different training modes for patients with different walking dysfunctions.

Patent literature CN113325720A discloses a rehabilitation training robot adaptive tracking control method with motion speed decision-making, which is characterized in that: compare the current motion speed of the rehabilitation training robot with the current walking speed of the trainer, and use the speed value of the comparison result as The state variable of the speed decision-making takes the acceleration, deceleration, and uniform motion of the rehabilitation training robot as the action of the speed decision-making, and designs the reward and punishment value function of the decision-making process according to the difference between the compared speed values to realize the motion speed decision-making of the rehabilitation training robot; use the decision-making motion speed The tracking error system is established based on the dynamics model of the rehabilitation training robot, and a tracking control method for the robot to adapt to the trainer's walking speed is proposed, so as to stabilize the error system and ensure the coordination of the human-machine system's movement speed. This solution is more difficult to implement, and the cost is higher.

To sum up, the lower limb robot speed control system and method proposed by the present invention aim to reduce production cost and implementation difficulty.

Contents of the invention

In view of the defects in the prior art, the object of the present invention is to provide a speed control system and method for a lower limb robot.

A lower limb robot speed control system provided according to the present invention includes:

Laser Doppler sensor module: fixed on the lower limb robot, emits laser light to the ground, and obtains the Doppler signal generated during the movement by collecting the scattered light on the ground;

Signal processing module: measure and calculate the characteristic frequency in the Doppler signal, and then measure the speed during the movement;

Speed adjustment module: adjust the speed of the next movement of the lower limb robot in real time according to the measured data;

Structural parts: the laser Doppler sensor module, signal processing module and speed adjustment module are fixed on the lower limb robot through structural parts.

Preferably, the laser Doppler sensor module includes a power supply, an optical element and a housing, the optical element includes a laser light source, a transmission grating, a diaphragm, a converging lens, a mirror, and a filter, and the laser light source is connected to a power supply;

The housing is divided into two spaces. The optical elements are arranged in the first space, and the optical elements are arranged in a double-beam optical path, and the power supply is placed in the second space.

Preferably, the signal processing module includes a photodetector and a data processing module, and the data processing module includes a digital oscilloscope, a computer and a data processing program;

The photodetector is arranged in the first space of the shell, collects the scattered light signal on the ground, and is connected with the oscilloscope in the data processing module to perform A/D conversion, and the computer is connected with the oscilloscope to read the A/D D converted binary digital signal, the data processing program processes the digital signal.

Preferably, the data processing program includes the following steps:

Step S1: establish a Doppler frequency shift model, and collect Doppler sensor signals;

Step S2: performing fast Fourier transform and bandpass filtering on the collected signal;

Step S3: Fit the characteristic frequency in the frequency spectrum with a Gaussian function, and take the mean value after fitting as the measured value of Doppler frequency shift.

Preferably, the speed adjustment module includes a driver, a belt and a servo motor;

The input end of the driver is connected to the data processing module, the output end is connected to the servo motor, the belt is used to place the driver, and the belt is used to fix the speed adjustment module.

Preferably, the step of controlling the movement speed by the driver includes:

Step S1: Determine a walking speed V that is most suitable for the patient as the speed that needs to be maintained during the training process;

Step S2: Comparing the velocity vt detected by the sensor during the patient training process with V to generate the velocity variation of the lower limb robot;

Step S3: The computer calculates the control amount of the servo motor according to the speed variation, and transmits the control amount to the driver, and the servo motor acts according to the instruction of the driver.

Preferably, the structural member includes a hexagon socket head cap screw, a flexible tube, a universal wheel and a bracket;

The inner hexagon countersunk head screw is used to fix the laser Doppler sensor module and the speed adjustment module, the flexible tube is used to place the wire, the universal wheel is fixed on the bracket, and the bracket is used to fix the digital oscilloscope and computer.

Preferably, when the patient is training on a smooth road, the Doppler frequency shift model is:

Among them, f _D1 and f _D2 are the Doppler frequency shift measured by the two laser Doppler sensors, v _x is the speed during training, and the speed measured by the sensor is v _t ≈ v _x , θ is incident on the ground The angle between the laser beam and the sensor housing, λ is the wavelength of the laser beam.

Preferably, when the patient is training on an uneven road surface, the Doppler frequency shift model is:

v _x is the velocity component of the lower-limb robot in the horizontal direction, v _y is the velocity component of the lower-limb robot in the vertical direction, and Δθ is the inclination angle between the shell and the horizontal direction; according to v _y << v _x in the walking process, the inclination angle Change to simplify:

The movement speed of the lower limb robot is:

A method for controlling the speed of a lower limb robot according to the present invention comprises the following steps:

Step A1: Through the laser Doppler sensor module, emit laser light to the ground, collect the scattered light on the ground to obtain the Doppler signal generated during the movement;

Step A2: measure and calculate the characteristic frequency in the Doppler signal, and then measure the speed during the movement;

Step A3: Adjust the speed of the next movement of the lower limb robot in real time according to the measured data.

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

1. The present invention innovatively applies the laser Doppler sensor to the wearable robot speed measurement system, which can directly measure the walking speed of the robot through the sensor. This sensor has high precision and high spatial resolution, and will not be affected by The impact caused by the vibration of the movement, and the optical path is stable, the thermal stability of the light source is good, the service life is long, and it is suitable for long-term work; the overall structure is highly integrated and compact;

2. The working principle of the present invention is simple, and the technical difficulty in realizing it is relatively low. Only by comparing the measured speed with the target speed, can the speed be adjusted;

3. The present invention has better interactivity, and patients can independently adjust the training speed during rehabilitation training;

4. The sensor used in the present invention can realize non-contact measurement, has fast response speed, does not need to collect a large amount of data, and has low cost.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Figure 1 is an overall schematic diagram of the lower limb robot speed control system;

Fig. 2 is a schematic structural diagram of a laser Doppler sensor module;

Fig. 3 is a schematic diagram of the structure of the dual-beam optical path of the laser Doppler sensor module.

Explanation of reference signs:

Power supply 1 Photodetector 9

Housing 2 Digital Oscilloscope 10

Laser light source 3 Computer 11

Transmission Grating 4 Driver 12

Aperture 5 Belt 13

Converging lens 6 Servo motor 14

Mirror 7 Universal wheel 15

Filter 8 Holder 16

detailed description

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

The present invention provides a speed control system for a lower limb robot. Referring to FIG. 1, it includes a laser Doppler sensor module, a signal processing module, a speed adjustment module and structural parts. The laser Doppler sensor module is fixed on the lower limb robot and The laser is emitted from the ground, and the Doppler signal generated during the movement is obtained by collecting the scattered light on the ground; the signal processing module measures the characteristic frequency in the Doppler signal, and then measures the speed during the movement; the speed adjustment module The speed of the next movement of the lower limb robot is adjusted in real time according to the measured speed; the laser Doppler sensor module, the signal processing module and the speed adjustment module are fixed on the lower limb robot through structural components.

Specifically, referring to Fig. 2, the laser Doppler sensor module includes a power supply 1, an optical element and a housing 2; A filter 8, the laser light source 3 is connected to a power supply 1, and the power supply 1 is a storage battery, which can be charged.

Further, the housing 2 is divided into two spaces. The optical components are arranged in the first space, and the optical components are arranged in a double-beam optical path. Referring to FIG. 3 , the power supply 1 is placed in the second space.

Further, in the double-beam optical path, the laser light source 3 emits a beam of light, which is scattered into multiple beams of diffracted light with equal light intensity after passing through the transmission grating 4, and collects zero-order and positive and negative first-order diffracted lights, which After the three beams pass through the first converging lens 6, they become three beams of parallel light. After the converging lens 6, the zero-order light is blocked by the diaphragm 5, and only the positive and negative first-order diffracted lights are allowed to pass, and the remaining two beams pass through the second one. After the converging lens 6 is focused on the ground, the two beams of light will generate interference fringes on the ground at this time. The interference fringes are an ellipsoid measuring body, which can be used to measure Doppler frequency shift. Then place a reflecting mirror 7 on the backward propagation direction of the light to receive the scattered light from the ground. The filter 8 is used to block the light of other wavelengths from entering, and finally the third converging lens 6 is placed after the filter 8 to focus the scattered light. Two identical double-beam optical paths are arranged in the first space, so that the angle between the incident light and the housing 2 is θ.

Specifically, the signal processing module includes a photodetector 9, a data processing module, and the data processing module includes a digital oscilloscope 10, a computer 11, and a data processing program.

Further, the photodetector 9 adopts an avalanche diode to receive the scattered light from the ground, and the photodetector 9 is placed at the focal point behind the third converging lens 6 to maximize the intensity of the scattered light received , so that the strength of the signal is maximized. After the photodetector 9 receives the signal and carries out the photoelectric conversion, it is still an analog signal, and the computer 11 cannot process it, so the photodetector 9 is connected to the two channels of the digital oscilloscope 10 earlier, and after the A/D conversion is carried out in the oscilloscope 10, It is then transmitted to the computer 11 for processing by a data processing program. The digital oscilloscope 10 also has an adjustment function, which can adjust the distance between the photodetector 9 and the third converging lens 6 according to the level on the oscilloscope. The higher the level, the more concentrated the signal and the better the quality of the collected signal.

Further, the data processing program includes the following steps:

Step S1: Establish the Doppler frequency shift model. When the patient performs rehabilitation training on a flat ground, the Doppler frequency shift measured by the Doppler sensor fixed on the lower extremity robot exoskeleton is

Among them: f _D1 and f _D2 are the Doppler frequency shift measured by two laser Doppler sensors, v _x is the speed during training, it can be considered that the speed measured by the sensor is v _t ≈ v _x , θ is incident to the ground The angle between the laser beam on the surface and the sensor housing 2, λ is the wavelength of the laser beam;

When the patient performs rehabilitation training on an uneven road surface, there will be an inclination angle Δθ between the sensor housing 2 and the horizontal direction, then the angle between the incident light direction of a Doppler sensor and the horizontal direction becomes θ+Δθ, and the other The angle between the incident light direction of a Doppler sensor and the horizontal direction becomes θ-Δθ. At this time, the lower limb robot not only has a velocity component v _x in the horizontal direction, but also a velocity component v _y in the vertical direction. At this time, the Doppler frequency shifts of the two Doppler sensors are respectively

In the process of walking: v _y << v _x , the change of inclination angle can be simplified as

The movement speed of the lower limb robot can be obtained as

Step S2: performing fast Fourier transform and bandpass filtering on the collected signal;

Step S3: Fit the characteristic frequency in the spectrum with a Gaussian function, the general form of the Gaussian function is

Take the fitted mean value μ as the measured value of Doppler frequency shift, and fit the Doppler signals of the two sensors. The measured values of Doppler frequency shift are respectively μ ₁ and μ ₂ , using the formula ( 5) The real-time movement speed of the lower limb robot can be obtained.

Data processing procedures include filtering, fast Fourier transform, and Gaussian fitting. Firstly, the signal is filtered to remove background noise and high-frequency noise. In the present invention, an FIR digital filter is selected, and a Hamming window is selected as a window function. Fast Fourier transform is performed after filtering to obtain the spectrum of the scattered light signal. There is a characteristic peak in the spectrum, and its corresponding abscissa is the Doppler frequency shift. Finally, in order to accurately estimate the Doppler frequency shift, and according to the similarity between the spectrum waveform and the Gaussian function, it is decided to use the Gaussian fitting technique, that is, to use the Gaussian function to fit the characteristic frequency in the spectrum. The general expression of the Gaussian function is as follows In formula (6), the mean value μ after fitting is taken as the measured value of Doppler frequency shift. Fitting the frequency spectrum of the two Doppler signals respectively can obtain μ ₁ and μ ₂ , and use these two estimated values as the estimated values of the two Doppler frequency shifts. According to (5), the walking speed can be calculated as

v _x =λ(μ ₁ +μ ₂ )/4cosθcosΔθ.

Specifically, the speed adjustment module includes a driver 12 , a belt 13 and a servo motor 14 . The input end of the driver 12 is connected with the computer 11 in the data processing module, the output end is connected with the servo motor 14, the servo motor 14 is installed at the hip joint, the power supply 1 supplies power to each component, and the The waist belt 13 is used to place the driver 12, and the speed adjustment module is tied on the patient's waist through the belt 13.

Further, the driver 12 selects the servo driver 12 of Elmo Company, its input end is connected to the computer 11, and the speed information v _t measured in the input data processing program is input into the expected training speed V in the computer 11 in advance. Compare and then make a decision. The decision-making process is as follows: There are three results of comparing the measured speed v _t with the expected speed V, namely v _t < V, v _t = V, v _t > V, respectively corresponding to the three control states of acceleration, constant speed and deceleration, using ΔV Indicates a speed change that the system needs to adjust at the end of the previous walking cycle, that is, ΔV=v _t -V, using v _t+1 to represent the speed of the next walking cycle, the three control states can be described as: for accelerated motion, v _t+1 =v _t +|ΔV|, v _t++ =v _t for uniform motion, and v _t+1 =v _t -|ΔV| for decelerated motion. The computer 11 calculates the control amount of the servo motor 14 according to the adjustment amount ΔV, the driver 12 is connected to the computer 11, and the motor control value is transmitted, and the servo motor 14 controls the swing frequency of the lower limbs according to the instruction of the driver 12, so as to achieve the speed adjustment. Purpose.

Specifically, the structural components include hexagon socket head screws, flexible tubes, universal wheels 15 and brackets 16 .

Further, the countersunk screw is used to fix the laser Doppler sensor module integrated in the housing 2, the flexible tube is used to wrap the wire, the universal wheel 15 is fixed at the bottom of the bracket 16, and the patient can face in any direction For walking training, the bracket 16 is used to fix the digital oscilloscope 10 and the computer 11, and it can also provide support for the patient, so that he can take a short rest during the training interval, and the patient can also observe the walking speed during training in real time, so as to do out adjustments.

The present invention also introduces a method for controlling the speed of a lower limb robot, comprising the following steps:

Step A1: Through the laser Doppler sensor module, emit laser light to the ground, collect the scattered light on the ground to obtain the Doppler signal generated during the movement;

Step A2: measure and calculate the characteristic frequency in the Doppler signal, and then measure the speed during the movement;

Step A3: Adjust the speed of the next movement of the lower limb robot in real time according to the measured data. .

The working principle of the present invention is as follows:

When the patient is performing walking rehabilitation training, he can input his own training speed through the computer (11) on the bracket (16). When the patient starts training, the light source (3) in the Doppler sensor emits a beam of light to the ground. After being scattered by the ground, the scattered light will be re-received by the photodetector (9), and the light signal will be converted by the digital oscilloscope (10). Pass into computer (11) after being the digital signal. Because of Doppler effect, this digital signal just contains Doppler frequency shift information, and computer (11) just can obtain the speed information at this moment by estimating this frequency shift, then according to corresponding formula, then this speed and input in advance The ideal speed is compared, and then the driver (12) performs decision-making control, so that the rotational speed of the motor changes, thereby changing the speed of the next training cycle, and the whole system also functions as a speed control.

Those skilled in the art know that, in addition to realizing the system provided by the present invention and its various devices, modules, and units in a purely computer-readable program code mode, the system provided by the present invention and its various devices can be completely programmed by logically programming the method steps. , modules, and units implement the same functions in the form of logic gates, switches, ASICs, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by the present invention can be regarded as a hardware component, and the devices, modules, and units included in it for realizing various functions can also be regarded as hardware components. The structure; the devices, modules, and units for realizing various functions can also be regarded as not only the software modules for realizing the method, but also the structures in the hardware components.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, rather than indicating or implying the referred device Or elements must have a certain orientation, be constructed and operate in a certain orientation, and thus should not be construed as limiting the application.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims (5)

1. A lower limb robot speed control system, characterized in that, comprising: Laser Doppler sensor module: fixed on the lower limb robot, emits laser light to the ground, and obtains the Doppler signal generated during the movement by collecting the scattered light on the ground; Signal processing module: measure and calculate the characteristic frequency in the Doppler signal, and then measure the speed during the movement; Speed adjustment module: adjust the speed of the next movement of the lower limb robot in real time according to the measured data; Structural parts: the laser Doppler sensor module, signal processing module and speed adjustment module are fixed on the lower limb robot through structural parts; The laser Doppler sensor module includes a power supply (1), an optical element and a housing (2), and the optical element includes a laser light source (3), a transmission grating (4), an aperture (5), and a converging lens (6) , reflector (7) and filter plate (8), described laser light source (3) is connected with power supply (1); The housing (2) is divided into two spaces, the optical elements are arranged in the first space, the optical elements are arranged in a double-beam optical path, and the power supply (1) is placed in the second space; The signal processing module includes a photodetector (9) and a data processing module, and the data processing module includes a digital oscilloscope (10), a computer (11) and a data processing program; The photodetector (9) is arranged in the first space of the casing (2), collects the scattered light signal on the ground, and is connected with the digital oscilloscope (10) in the data processing module to perform A/D conversion, so Described computer (11) is connected with digital oscilloscope (10), reads the binary digital signal after A/D conversion, and described data processing program processes digital signal; The data processing procedure includes the following steps: Step S1: establish a Doppler frequency shift model, and collect Doppler sensor signals; Step S2: performing fast Fourier transform and bandpass filtering on the collected signal; Step S3: Fitting the characteristic frequency in the frequency spectrum with a Gaussian function, taking the mean value after fitting as the measured value of Doppler frequency shift; When the patient is training on a smooth road, the Doppler frequency shift model is:

Among them, f _D1 and f _D2 are the Doppler frequency shift measured by the two laser Doppler sensors, v _x is the speed during training, and the speed measured by the sensor is v _t ≈ v _x , θ is incident on the ground The angle between the laser beam and the sensor housing (2), λ is the wavelength of the laser beam; When the patient is training on an uneven road surface, the described Doppler frequency shift model is:

v _x is the velocity component of the lower-limb robot in the horizontal direction, v _y is the velocity component of the lower-limb robot in the vertical direction, and Δθ is the inclination angle between the shell (2) and the horizontal direction; according to v _y << v _x , simplifying the inclination variation:

The movement speed of the lower limb robot is:

2. The lower limb robot speed control system according to claim 1, characterized in that: the speed adjustment module includes a driver (12), a waist belt (13) and a servo motor (14); The input end of the driver (12) is connected to the data processing module, the output end is connected to the servo motor (14), the belt (13) is used to place the driver (12), and the belt (13) is used to for fixed speed regulation modules. 3. lower limb robot speed control system according to claim 2, is characterized in that: described driver (12) comprises to the control step of motion speed: Step S1: Set a walking speed V suitable for the patient as the speed to be maintained during the training process; Step S2: Comparing the velocity v _t detected by the sensor during the patient training process with V to generate the velocity variation of the lower limb robot; Step S3: The computer (11) calculates the control amount of the servo motor (14) according to the speed variation, and transmits the control amount to the driver (12), and the servo motor (14) acts according to the instruction of the driver (12). 4. The lower limb robot speed control system according to claim 1, characterized in that: the structural member comprises a hexagon socket head screw, a flexible tube, a universal wheel (15) and a bracket (16); The inner hexagon socket head screw is used to fix the laser Doppler sensor module and the speed adjustment module, the flexible tube is used to place the wire, the universal wheel (15) is fixed on the support (16), and the support ( 16) It is used to fix the digital oscilloscope (10) and computer (11). 5. A lower limb robot speed control method, is characterized in that, comprises the following steps: Step A1: Through the laser Doppler sensor module, emit laser light to the ground, collect the scattered light on the ground to obtain the Doppler signal generated during the movement; Step A2: measure and calculate the characteristic frequency in the Doppler signal, and then measure the speed during the movement; Step A3: Adjust the speed of the next movement of the lower limb robot in real time according to the measured data.

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