Powered exoskeleton assist control device and method thereof

Abstract

The application provides a power exoskeleton assisting control device and a method thereof, wherein a desired assisting curve is generated through parameters and gait states, a difference between the desired assisting curve and a tension force measured by a tension force sensor on a muscle exoskeleton is put into a PID controller, an ankle joint angular velocity is put into a gain device to obtain an ankle joint angular velocity feedforward control amount, the control amount generated by the PID controller and the ankle joint angular velocity feedforward control amount are used to generate a desired motor speed, a measured actual motor speed is used to generate a difference between the desired motor speed and the actual motor speed, the difference is put into a PI controller, a control amount generated by the controller is a desired motor current, the desired motor current is used to generate a difference between the desired motor current and an actual motor current, the difference is put into another PI controller, so that the motor current is tracked and controlled, and the assisting purpose is achieved.

Description

[Technical Field]

[0001] This invention relates to the field of wearable exoskeleton technology, specifically to a powered exoskeleton assistive control device and method. [Background Technology]

[0002] Wearable exoskeletons have wide applications in military, medical, and industrial fields. Using exoskeletons can reduce the wearer's load, helping them move better and more effortlessly. Typically, exoskeletons use self-powered propulsion to assist the wearer's movement; these are also called powered exoskeletons. In the medical field, exoskeletons can provide real-time walking assistance to patients undergoing rehabilitation. For patients with impaired mobility, the control methods of exoskeletons must achieve good human-machine coordination, rapid response, and real-time accurate recognition and reaction to asynchrony with normal individuals, providing accurate and adjustable timing and magnitude of assistance. On the other hand, for patients undergoing rehabilitation, their walking speed gradually recovers from an initially slow pace to a normal or faster walking speed. However, existing assistive control schemes are suitable for slow speeds and do not provide effective assistance for fast walking. [Summary of the Invention]

[0003] The purpose of this invention is to provide a powered exoskeleton assistive control device, which is applied in the field of rehabilitation to effectively assist the ankle joint of users undergoing rehabilitation training when walking.

[0004] Another objective of this invention is to provide a powered exoskeleton assistive control method, which is applied in the field of rehabilitation to effectively assist the ankle joint of users undergoing rehabilitation training when walking.

[0005] In a first aspect, embodiments of the present invention provide a powered exoskeleton assistive control device, comprising:

[0006] Expectation-Boosting Generator: Generates expected goals;

[0007] Tension acquisition unit: Acquires tension data from the tension sensors on the powered exoskeleton;

[0008] Tension subtraction unit: It subtracts the tension target generated by the expected assist generator from the tension data acquired by the tension acquisition unit to obtain the tension error;

[0009] PID controller: Used to store the tension error data output by the tension difference unit, and to generate the expected motor speed based on the tension error data;

[0010] Ankle joint angular velocity feedforward compensation unit: amplifies the human ankle joint angular velocity to obtain the ankle joint angular velocity feedforward control quantity; Desired motor speed generation unit: generates the desired motor speed based on the control quantity generated by the PID controller and the ankle joint angular velocity feedforward control quantity;

[0011] Motor speed acquisition unit: Acquires the actual motor speed of the motor in the power exoskeleton assist control device;

[0012] Motor speed difference unit: Performs difference processing on the desired motor speed and the actual motor speed to obtain the motor speed error;

[0013] Desired motor current generation unit: Generates the desired motor current based on the motor speed error;

[0014] Actual motor current acquisition unit: acquires the actual motor current data of the motor of the power exoskeleton assistive control device;

[0015] Motor current difference unit: Subtracts the desired motor current from the actual motor current to obtain the current error;

[0016] Current controller: Stores current error and tracks and controls motor current based on current error.

[0017] In one possible design, the system further includes an ankle joint angular velocity acquisition unit, a low-pass filter, and a gainer. The ankle joint angular velocity acquisition unit obtains the ankle joint angular velocity by processing data jointly measured by a calf inertial sensor and a foot inertial sensor. The low-pass filter filters the obtained ankle joint angular velocity to reduce high-frequency noise and obtain a low-frequency signal that conforms to human joint movement. The gainer amplifies the filtered ankle joint angular velocity. The ankle joint angular velocity feedforward compensation unit includes the gainer, which obtains the ankle joint angular velocity feedforward control quantity based on the information from the low-pass filter and the gain information.

[0018] In one possible design, the desired assistance generator obtains external smart terminal setting parameters and gait status to generate a desired assistance target.

[0019] In one possible design, the desired assist target is a Sine curve, the peak value of which is provided by the assist parameter value input by the smart terminal, and the starting point and period length of the Sine curve are provided by gait information.

[0020] In one possible design, the actual motor speed is measured by a motor encoder; the actual motor current is measured by a motor ammeter; and the current controller includes a PI controller.

[0021] Secondly, embodiments of the present invention provide a powered exoskeleton assistance control method, comprising:

[0022] a) Generate desired assistance targets based on gait status;

[0023] b) The difference between the expected assist target and the tension measured by the tension sensor on the powered exoskeleton is used to obtain the tension error;

[0024] c) The tension error is stored in the PID controller to generate the desired motor speed;

[0025] d) Obtain the ankle joint angular velocity and filter and gain the ankle joint angular velocity to obtain the ankle joint angular velocity feedforward control quantity;

[0026] e) The desired motor speed is generated by combining the control input generated by the PID controller and the ankle joint angular velocity feedforward control input;

[0027] f) Obtain the actual speed of the motor;

[0028] g) Subtract the desired motor speed from the actual motor speed to obtain the motor speed error;

[0029] h) The motor speed error is fed into the PI controller to generate the desired motor current control quantity;

[0030] i) Obtain the actual current of the motor;

[0031] g) Calculate the difference between the expected motor current and the actual motor current to obtain the current error;

[0032] k) The current error is stored in the current controller, and the motor current is tracked and controlled based on the current error.

[0033] In one possible design, the ankle joint angular velocity is acquired by processing data jointly measured by a lower leg inertial sensor and a foot inertial sensor; the ankle joint angular velocity is filtered by using a low-pass filter to reduce high-frequency noise in the ankle joint angular velocity signal to obtain a low-frequency signal that conforms to human joint movement; the ankle joint angular velocity is amplified by a gain converter; and the ankle joint angular velocity feedforward control quantity is obtained by using information sent from the low-pass filter and the amplified information.

[0034] In one possible design, the desired assist target is generated by acquiring settings parameters from an external smart terminal and gait status.

[0035] In one possible design, the desired assist target is a Sine curve, the peak value of which is provided by the assist parameter value input by the smart terminal, and the starting point and period length of the Sine curve are provided by gait information.

[0036] In one possible design, the actual motor speed is obtained through a motor encoder; the actual motor current is obtained through a motor ammeter; and the current controller includes a PI controller.

[0037] The powered exoskeleton assistive control device and method of the present invention adopts proportional-integral-derivative (PID) control and feedforward control. By using the feedforward compensation amount of ankle joint angular velocity, the control error of the assist is smaller, providing a better assist effect for fast walking, and solving the problem that the assist cannot keep up when walking fast in traditional force control methods.

[0038] Meanwhile, in this invention, when generating assistance goals, parameter values ​​are provided through an external smart terminal, allowing doctors to set different assistance goals according to the patient's actual situation, thus more effectively helping the patient with rehabilitation training.

[0039] In addition, this invention generates assistance targets while simultaneously generating them based on the patient's real-time gait information, thus providing more precise assistance according to the patient's real-time condition. [Image Description]

[0040] Figure 1 This is a schematic diagram of the functional modules of the powered exoskeleton assistive control device of the present invention;

[0041] Figure 2 This is a schematic diagram of the power exoskeleton assistive control method of the present invention;

[0042] Figure 3 This is a schematic diagram illustrating the relationship between the ankle joint and the pull rope when the present invention is applied to an exoskeleton device under assisted conditions;

[0043] Figure 4 This is an embodiment of the present invention applied to the assist control of a powered exoskeleton. [Detailed Implementation]

[0044] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following description, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the exoskeleton frame and its application device proposed according to the present invention. The following embodiments are provided to further describe the present invention, but the described embodiments are only for illustrative purposes and are not intended to limit the present invention.

[0045] Please see Figure 1 The diagram shown is a functional module schematic of the powered exoskeleton assistive control device of the present invention. The powered exoskeleton assistive control device of the present invention includes:

[0046] Expectation-Boosting Generator: Generates expected goals;

[0047] Tension acquisition unit: Acquires tension data from the tension sensors on the powered exoskeleton;

[0048] Tension subtraction unit: It subtracts the tension target generated by the expected assist generator from the tension data acquired by the tension acquisition unit to obtain the tension error;

[0049] PID controller: Used to store the tension error data output by the tension difference unit and generate the desired motor speed based on the tension error data;

[0050] Ankle joint angular velocity feedforward compensation unit: Gains the human ankle joint angular velocity to obtain the ankle joint angular velocity feedforward control quantity;

[0051] Desired motor speed generation unit: Based on the control quantity of the PID controller to generate the motor's expected speed and the ankle joint angular velocity feedforward control quantity, the desired motor speed, i.e. the target of motor speed tracking, is generated together.

[0052] The motor's expected speed control quantity generated by the PID controller fine-tunes the assist to ensure that the tracking error is small enough; the ankle joint angular velocity feedforward control quantity provides an auxiliary adjustment to the assist, effectively accelerating the control tightening speed of the pull rope and reducing interference caused by ankle joint rotation.

[0053] Motor speed acquisition unit: Acquires the actual motor speed of the motor in the power exoskeleton assist control device;

[0054] Motor speed difference unit: Performs difference processing on the desired motor speed and the actual motor speed to obtain the motor speed error;

[0055] Desired motor current generation unit: Generates the desired motor current based on the motor speed error;

[0056] Actual motor current acquisition unit: acquires the actual motor current data of the motor of the power exoskeleton assistive control device;

[0057] Motor current difference unit: Subtracts the desired motor current from the actual motor current to obtain the current error;

[0058] Current controller: Stores current error and tracks and controls motor current based on current error.

[0059] Preferably, the powered exoskeleton assistive control device further includes an ankle joint angular velocity acquisition unit, a low-pass filter, and a gainer. The ankle joint angular velocity acquisition unit obtains the ankle joint angular velocity by processing data jointly measured by a calf inertial sensor and a foot inertial sensor. The low-pass filter filters the obtained ankle joint angular velocity to reduce high-frequency noise and obtain a low-frequency signal consistent with human joint movement. The gainer amplifies the filtered ankle joint angular velocity. The ankle joint angular velocity feedforward compensation unit obtains the ankle joint angular velocity feedforward control quantity based on the information from the low-pass filter and the information sent by the gainer. In this embodiment, the ankle joint angular velocity feedforward control quantity calculated by the gainer is the ankle joint angular velocity feedforward control quantity output after amplification by the gainer.

[0060] The desired assistance generator acquires settings parameters from an external smart terminal and gait status to generate a desired assistance target. In a preferred embodiment, the desired assistance target is a Sine curve, where the peak value of the Sine curve is provided by the assistance parameter value input from the smart terminal, and the starting point and period length of the Sine curve are provided by gait information.

[0061] In this embodiment, the actual motor speed is measured by a motor encoder; the actual motor current is measured by a motor ammeter; the current controller includes a PI controller, which decouples the obtained q-axis and d-axis currents into DC variables, generates control quantities through the PI controller, and then controls the amplitude, frequency, and phase of the three-phase current.

[0062] like Figure 2 The flowchart shown is a power exoskeleton assistive control method of the present invention, which includes the following steps:

[0063] a) Generate desired assistance targets based on gait status;

[0064] b) The difference between the expected assist target and the tension measured by the tension sensor on the powered exoskeleton is used to obtain the tension error;

[0065] c) The tension error is stored in the PID controller to generate the motor's expected speed;

[0066] d) Obtain the ankle joint angular velocity and filter and gain the ankle joint angular velocity to obtain the ankle joint angular velocity feedforward control quantity;

[0067] e) The desired motor speed is generated by combining the expected speed generated by the PID controller and the feedforward control quantity of the ankle joint angular velocity;

[0068] f) Obtain the actual speed of the motor;

[0069] g) Subtract the desired motor speed from the actual motor speed to obtain the motor speed error;

[0070] h) The motor speed error is fed into the PI controller to generate the desired motor current control quantity;

[0071] i) Obtain the actual current of the motor;

[0072] j) The difference between the expected motor current and the actual motor current is used to obtain the current error;

[0073] k) The current error is stored in the current controller, and the motor current is tracked and controlled based on the current error, thereby realizing the tracking control of the motor current.

[0074] In step d), the ankle joint angular velocity is acquired by processing data jointly measured by the lower leg inertial sensor and the foot inertial sensor; the ankle joint angular velocity is filtered by using a low-pass filter to reduce high-frequency noise in the ankle joint angular velocity signal, obtaining a low-frequency signal consistent with human joint movement; the ankle joint angular velocity is amplified by a gain converter; and the ankle joint angular velocity feedforward control quantity is obtained by using information from the low-pass filter and information amplified by the gain converter. In this embodiment, the ankle joint angular velocity feedforward control quantity is calculated using a gain converter.

[0075] In step a), the desired assistance target is generated by acquiring external smart terminal settings and gait status. In this embodiment, the desired assistance target is a Sine curve, the peak value of which is provided by the assistance parameter value input by the smart terminal, and the starting point and period length of the Sine curve are provided by gait information.

[0076] In step f), the actual motor speed is obtained through a motor encoder.

[0077] In step i), the actual motor current is obtained by using the motor's ammeter.

[0078] In step k), the current controller includes a PI controller.

[0079] like Figure 3 The diagram illustrates an embodiment of the invention, applied to an exoskeleton device, showing the relationship between the ankle joint and the pull rope under assisted conditions. Let the distance between the two anchor points of the pull rope on the exoskeleton leg support be d (the distance from the heel fixation point to the lower leg fixation point), the ankle joint's rotation radius be r (the distance from the ankle joint to the heel fixation point), and the ankle joint angle be θ. Under this structural design, the following model relationship is established: Δd = -r·Δθ. As the ankle joint angle changes, the distance between the two anchor points changes accordingly. Δθ can be calculated using inertial sensors on the lower leg and foot, and also based on the radius r of the motor pulley.pully The gain of the gain amplifier is then calculated to be r / r_. pully A low-pass filter filters the ankle joint angular velocity, ω. c ω is the cutoff frequency of the low-pass filter. foot Let ω be the angular velocity of the foot. shank Given the lower leg angular velocity, the ankle joint angular velocity feedforward control quantity ω is obtained using the following formula. mot In this embodiment, the ankle joint angular velocity feedforward control value is calculated using a gain converter. This embodiment compensates for the impact of ankle joint rotation on Bowden line assistance through ankle joint angular velocity feedforward control. Under this control, the rope (Bondden line) can maintain a basic tautness. Maintaining rope tautness is a fundamental condition for providing assistance. The ω... mot The negative sign indicates the laying state, ω mot A plus sign indicates the wire is being collected.

[0080]

[0081] The ankle joint angular velocity feedforward control quantity obtained by filtering with a low-pass filter is combined with the motor's expected speed generated by the PID controller to obtain the motor's desired speed. This reduces overshoot and oscillation in the power assist control, improves the robustness of the power assist control, and enhances user comfort and safety.

[0082] Please also refer to Figure 4 This invention is an embodiment of the assistive control of a powered exoskeleton. In this embodiment, a desired assist curve is generated based on parameters set by a smart terminal and gait status. The difference between the desired assist curve and the tension measured by the tension sensor on the powered exoskeleton is fed into a PID controller. The ankle joint angular velocity is jointly measured by the lower leg inertial sensor and the instep (or foot) inertial sensor on the powered exoskeleton. After being filtered by a low-pass filter, amplified by a gain converter, and the ankle joint angular velocity feedforward control quantity is calculated. The control quantity generated by the PID controller and the ankle joint angular velocity feedforward control quantity together generate the desired motor speed. Then, the motor encoder measures the actual motor speed. The difference between the desired motor speed and the actual motor speed is fed into a PI controller, and the controller generates the desired motor current. Then, the motor ammeter measures the actual motor current. The difference between the desired motor current and the actual motor current is fed into another PI controller, thereby achieving tracking control of the motor current, controlling the motor to output the corresponding torque, and thus controlling the tension or relaxation of the cables on the powered exoskeleton. This invention achieves the goal of effectively providing assistance to the patient according to the desired assist target.

[0083] The powered exoskeleton assistive control device and method of the present invention adopts proportional-integral-derivative (PID) control and feedforward control. By using the feedforward compensation amount of ankle joint angular velocity, the control error of the assist is smaller, providing a better assist effect for fast walking, and solving the problem that the assist cannot keep up when walking fast in traditional force control methods.

[0084] Meanwhile, in this invention, when generating assistance goals, parameter values ​​are provided through an external smart terminal, allowing doctors to set different assistance goals according to the patient's actual situation, thus more effectively helping the patient with rehabilitation training.

[0085] In addition, this invention generates assistance targets while simultaneously generating them based on the patient's real-time gait information, thus providing more precise assistance according to the patient's real-time condition.

[0086] In this specification, the invention has been described with reference to specific embodiments thereof; however, it will be apparent that various modifications and variations can be made without departing from the spirit and scope of the invention. Therefore, the specification and drawings are to be considered illustrative rather than restrictive.

Claims

1. A powered exoskeleton assistive control device, characterized in that, include: Expectation-Boosting Generator: Generates expected goals; Tension acquisition unit: Acquires tension data from the tension sensors on the powered exoskeleton; Tension subtraction unit: It subtracts the tension target generated by the expected assist generator from the tension data acquired by the tension acquisition unit to obtain the tension error; PID controller: Used to store the tension error data output by the tension difference unit, and to generate the expected motor speed based on the tension error data; Ankle joint angular velocity feedforward compensation unit: Gains the human ankle joint angular velocity to obtain the ankle joint angular velocity feedforward control quantity; Desired motor speed generation unit: Generates the desired motor speed based on the control quantity generated by the PID controller and the ankle joint angular velocity feedforward control quantity; Motor speed acquisition unit: Acquires the actual motor speed of the motor in the power exoskeleton assist control device; Motor speed difference unit: Performs difference processing on the desired motor speed and the actual motor speed to obtain the motor speed error; Desired motor current generation unit: Generates the desired motor current based on the motor speed error; Actual motor current acquisition unit: acquires the actual motor current data of the motor of the power exoskeleton assistive control device; Motor current difference unit: Subtracts the desired motor current from the actual motor current to obtain the current error; Current controller: Stores current error and tracks and controls motor current based on current error.

2. The powered exoskeleton assistive control device as described in claim 1, characterized in that: It also includes an ankle joint angular velocity acquisition unit, a low-pass filter, and a gainer; the ankle joint angular velocity acquisition unit obtains the ankle joint angular velocity by processing data jointly measured by the calf inertial sensor and the foot inertial sensor; the low-pass filter filters the obtained ankle joint angular velocity to reduce high-frequency noise in the signal and obtain a low-frequency signal that conforms to human joint movement; the gainer amplifies the filtered ankle joint angular velocity; the ankle joint angular velocity feedforward compensation unit includes the gainer, which obtains the ankle joint angular velocity feedforward control quantity based on the information from the low-pass filter and the gain information.

3. The powered exoskeleton assistive control device as described in claim 1, characterized in that: The desired assistance generator obtains the settings parameters of the external smart terminal and the gait status to generate the desired assistance target.

4. The powered exoskeleton assistive control device as described in claim 3, characterized in that: The desired assistance target is a Sine curve, the peak value of which is provided by the assistance parameter value input by the smart terminal, and the starting point and period length of the Sine curve are provided by gait information.

5. The powered exoskeleton assistive control device as described in claim 1, characterized in that: The actual motor speed is measured by a motor encoder; the actual motor current is measured by a motor ammeter; the current controller includes a PI controller.

6. A power exoskeleton assistive control method, characterized in that, include: a) Generate desired assistance targets based on gait status; b) The difference between the expected assist target and the tension measured by the tension sensor on the powered exoskeleton is used to obtain the tension error; c) The tension error is stored in the PID controller to generate the desired motor speed; d) Obtain the ankle joint angular velocity and filter and gain the ankle joint angular velocity to obtain the ankle joint angular velocity feedforward control quantity; e) The desired motor speed is generated by combining the control input generated by the PID controller and the ankle joint angular velocity feedforward control input; f) Obtain the actual speed of the motor; g) Subtract the desired motor speed from the actual motor speed to obtain the motor speed error; h) The motor speed error is fed into the PI controller to generate the desired motor current control quantity; i) Obtain the actual current of the motor; g) Calculate the difference between the expected motor current and the actual motor current to obtain the current error; k) The current error is stored in the current controller, and the motor current is tracked and controlled based on the current error.

7. The powered exoskeleton assistive control method as described in claim 6, characterized in that, The ankle joint angular velocity is obtained by processing data jointly measured by the lower leg inertial sensor and the foot inertial sensor; the ankle joint angular velocity is filtered by using a low-pass filter to reduce high-frequency noise in the ankle joint angular velocity signal to obtain a low-frequency signal that conforms to human joint movement; the ankle joint angular velocity is amplified by a gain converter; the ankle joint angular velocity feedforward control quantity is obtained by using information sent from the low-pass filter and the amplified information.

8. The powered exoskeleton assistive control method as described in claim 6, characterized in that, The desired assistance target is generated by acquiring the settings parameters of an external smart terminal and the gait status.

9. The powered exoskeleton assistive control method as described in claim 8, characterized in that, The desired assistance target is a Sine curve, the peak value of which is provided by the assistance parameter value input by the smart terminal, and the starting point and period length of the Sine curve are provided by gait information.

10. The powered exoskeleton assistive control method as described in claim 6, characterized in that, The actual motor speed is obtained through a motor encoder; the actual motor current is obtained through a motor ammeter; the current controller includes a PI controller.

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