Bowden cable assisted flexible lower limb multi-joint exoskeleton robot and control method

Abstract

The invention belongs to the technical field of motorized tools, and particularly relates to a Bowden cable power-assisted flexible lower limb multi-joint exoskeleton robot and a control method. The robot can assist the hip and knee joints of the lower limbs when a human body walks; a reversing bevel gear set, a two-way wire spool and an electromagnetic clutch are adopted, so that a single motor assists hip joint extension and knee joint bending in the left leg and the right leg of the lower limb; the prediction of the walking gait position and the gait period is realized through inertial measurement units mounted on the two sides of the left leg and the right leg; in the control system, an upper computer drives a motor through dspace to drive hip and knee joints of lower limbs to move, an inertial measurement unit performs angle feedback, and normalized gait prediction is realized. Through a designed dynamic model, PD iterative control and fuzzy PID control, the tracking of the hip and knee joint expected power-assisted curve is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of motorized tools, and in particular relates to a Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot and a control method thereof. Background Art

[0002] The number of elderly people and those suffering from lower limb dysfunction due to accidental injuries has increased significantly, severely impacting their quality of life and placing a heavy burden on families and society. Currently, rehabilitation treatments primarily rely on Traditional Chinese Medicine (TCM) and simple assistive devices, but medical resources are limited and unable to meet individual needs. Therefore, improving lower limb mobility and quality of life for the elderly and those with motor dysfunction has become a pressing public health issue.

[0003] An exoskeleton is a human-machine interactive robotic system worn externally on the human body that moves in coordination with it. Its purpose is to provide support and assist limb movement, thereby enhancing human function. It has a wide range of applications in both civilian and military fields. In the civilian sector, exoskeletons are primarily used to assist walking for people with disabilities, elderly people with limited mobility, and some patients with motor impairments, reducing the socioeconomic burden of aging and rehabilitation. Furthermore, in industrial and rescue scenarios, exoskeletons can assist in the lifting of heavy objects, significantly improving production and rescue efficiency. In the military, exoskeletons are used to enhance soldiers' combat capabilities and endurance. Lower-limb exoskeletons combine artificial intelligence with mechanical power to significantly improve walking endurance and load capacity. Although traditional rigid exoskeletons offer good assistance, their high inertia, interference with the body's natural gait, and difficulty in precisely aligning mechanical and human joints limit their application and development.

[0004] Flexible exoskeletons are gradually replacing bulky rigid exoskeletons due to their advantages, such as less restrictiveness and strong biomimetic properties. Flexible exoskeletons not only reduce pressure on the skin but also increase the autonomy of the power-assisting device and the convenience of daily use, making them highly popular in the field of assisted walking.

[0005] By strategically arranging flexible assistance modules, drive units, and sensors, flexible lower-limb assistance exoskeletons can effectively coordinate with the kinematics of the human lower limb during movement. This allows them to provide assistance at the right moment, thereby reducing muscle activation in the corresponding lower limb muscle groups. However, existing flexible lower-limb assistance exoskeletons suffer from insufficient assistance precision and poor performance, making them difficult to use in daily life. Summary of the Invention

[0006] The purpose of the present invention is to provide a Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot and control method, which can solve the problems of the lower limb exoskeleton robot in which one motor drives one joint to move, the driving device is heavy, the flexibility is poor, and it is inconvenient to wear. The robot is easy to wear and light in weight, and can be worn and used by people of different weights. It provides flexible assistance to the lower limbs, combines a tension sensor with an inertial measurement unit, identifies and predicts movement intentions, and achieves precise control of the assistance curve through iterative learning control algorithm and fuzzy PID control algorithm.

[0007] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0008] The present invention provides a Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, comprising an integrated wearable exoskeleton suit, a drive device, and a Bowden cable; the drive device is installed on the shoulder strap portion of the integrated wearable exoskeleton suit, and the drive device provides power to the integrated wearable exoskeleton suit via the Bowden cable;

[0009] The driving device includes a motor, a motor support frame, a driving back plate, a Bowden cable reversing wheel, a sensor support frame, a reversing bevel gear set, an electromagnetic clutch, a parallel elastic unit, a gear shaft and a bidirectional driving disk; the motor support frame and the driving back plate are installed on the shoulder strap part, the motor is installed on the motor support frame, two driving back plates are symmetrically installed on both sides of the motor support frame, each of the driving back plates is movably supported with a gear shaft, the output shaft of the motor is connected to the inner ends of the two gear shafts through the reversing bevel gear set, and the outer end of the gear shaft is connected to the bidirectional driving disk via the electromagnetic clutch and the parallel elastic unit.

[0010] Furthermore, in the above-mentioned Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, the integrated wearable exoskeleton suit includes a tights base, a belt drive module, a thigh drive module and a calf drive module. The thigh drive module is connected to the belt drive module located above it and the calf drive module located below it through module connecting nylon belts, and the bottom end of the calf drive module is connected to the tights base; the drive device realizes a single motor to assist the hip joint extension and knee joint flexion in the left and right legs of the lower limbs through a reversing bevel gear set, an electromagnetic clutch and a bidirectional winding disk.

[0011] Furthermore, in the above-mentioned Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, the belt drive module is located at the waist of the human body and uses nylon and nylon materials as the base; Velcro is sewn on the inside of the belt to ensure that it remains in a fixed position during exercise; during the power-assisting process, the power transmission belt transmits force to the iliac crest area of ​​the pelvis, so this part uses silicone flexible material to disperse pressure and improve fit with the body; in order to increase the stiffness of the anchor point position and evenly distribute the force on the waist, nylon webbing is sewn on the base of the tights, and the power transmission webbing is sewn in a "V" shape to transmit force to the opening of the belt; the nylon webbing of the anchor point is sewn in a "V" shape. The belt is sewn in a molded manner and is equipped with a first sleeve fixing device and a Bowden line reversing wheel at a key position. The belt driving module is fixed at both ends with air eyelets.

[0012] Furthermore, in the above-mentioned Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, the thigh drive module is located in the middle of the human thigh and uses the same base material as the waist belt drive module; the thigh drive module is sewn with a "V"-shaped low-temperature thermoplastic plate on the side, and a Bowden cable end fixing device is set at the top to ensure efficient transmission of tension; the lower side is sewn with The low-temperature thermoplastic plate is equipped with a second sleeve fixing device and a Bowden cable reversing wheel to reduce friction; the end Velcro is connected to the belt drive module, and the shape of the thigh drive module fits the thigh to prevent sliding when the motor is driven.

[0013] Furthermore, in the above-mentioned Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, the calf drive module is located in the middle of the human calf, adopts a nylon base, and sews a low-temperature thermoplastic plate to increase the anchor point stiffness and disperse the force.

[0014] Furthermore, in the above-mentioned Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, a main control box is installed above the driving device, and the main control box includes a controller, a motor driver, a signal amplifier and a lithium battery. The main control box is connected to the driving device through corresponding wires.

[0015] Furthermore, in the above-mentioned Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, the driving backplate includes an upper backplate and a lower backplate; the upper backplate has a boss in the middle and depressions on both sides; the single-chip microcomputer and the signal amplifier are fixed on the upper backplate by threaded connection, and the lithium battery is embedded in the groove of the upper backplate; the two sides of the lower backplate are through holes for facilitating the motor, motor support frame, reversing bevel gear set, electromagnetic clutch, parallel elastic unit and bidirectional drive disk.

[0016] Furthermore, in the above-mentioned Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, the parallel elastic unit adopts a modular structure, consisting of a pre-tightening bolt, a sleeve fixing block, a parallel spring and a parallel spring tube; the initial pre-tightening force of the Bowden cable is adjusted by the pre-tightening bolt. During the movement of the Bowden cable, the friction between the Bowden cable and the Bowden cable tube drives the displacement of the sleeve fixing block, thereby compressing the parallel spring in the parallel spring tube to achieve passive compliance function.

[0017] The present invention also provides a Bowden cable-assisted flexible lower limb multi-joint exoskeleton control method, characterized in that the equipment used in the control method includes a host computer system and the Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot as described above, the host computer system includes a dspace host computer, the dspace host computer can obtain the hip joint motion angle collected by all inertial measurement units of the lower limb exoskeleton robot and the Bowden cable end tension collected by the tension sensor, and transmit them back to the host computer to realize force / displacement closed-loop control; the controller in the main control box is electrically connected to all IMU inertial measurement units of the lower limb exoskeleton robot at the same time, and can obtain gait information collected by all IMU inertial measurement units of the lower limb exoskeleton robot, the inertial measurement units are installed in the middle of the left and right thighs, and tension sensors are installed on the Bowden cable end fixing devices of the hip and knee joints of the left and right legs; the controller controls the operation of the corresponding motors in the drive device through the motor driver;

[0018] The control method comprises the following steps:

[0019] S1. The driving device is placed on the back, and the shoulder straps are used to tightly fit the driving device and the back of the human body. The inertial measurement unit collects the rotation angle information of the thigh and hip joint to realize the recognition of human movement intention;

[0020] S2. A tension sensor collects tension information at the end of the Bowden cable. A dynamic equation for the flexible lower limb exoskeleton is established to derive the relationship between the joint assist value and the Bowden cable displacement. The desired assist force is converted into the desired displacement. A PD iterative learning controller is used to compensate for the position error to eliminate periodic errors.

[0021] S3. Finally, the displacement signal is used to dynamically control the motor through the fuzzy PID algorithm.

[0022] Furthermore, during the gait cycle, there is an overlapping area between the right hip extension torque and the left knee flexion torque. To avoid interfering with the normal movement of the knee joint, the power assist should be terminated when the knee flexion velocity is at its maximum. At this time, the right hip extension has not yet been completed. The gait cycle is defined as from the right toe leaving the ground to leaving the ground again, rather than the heel touching the ground. Because the sum of the power change ranges of the two joints is less than half of the gait cycle, the motor has sufficient time to perform the reversing operation, achieving power assist for left hip extension and right knee flexion through forward and reverse rotation.

[0023] The electromagnetic clutch is switched on and off at specific times, enabling a single motor to assist in hip extension and knee flexion of the left and right legs;

[0024] The inertial measurement unit collects information on the rotation angle of the thigh hip joint. The plantar pressure sensor collects plantar pressure changes during the gait cycle, achieving the maximum hip joint extension angle to map the toe-off event and predict key gait positions. The time difference between two adjacent maximum hip joint extension angles is used as the gait cycle, and a weighted prediction method is used to estimate the current gait cycle value using the previous three gait cycle values.

[0025] The angle information collected by all inertial measurement units and the Bowden cable tension collected by the tension sensor are sent to the DSpace host computer and the controller at the same time. Gait recognition is performed on the DSpace host computer to determine the current gait position. The DSpace host computer will identify the gait position and transmit it to the controller. The controller adopts the corresponding power assistance strategy based on the identified gait position, and realizes the tracking of the desired power assistance curve of the hip and knee joints through the designed dynamic model, PD iterative control and fuzzy PID control.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention provides a Bowden cable-assisted flexible lower-limb multi-joint exoskeleton robot that assists the hip and knee joints during walking. A reversing bevel gear set, a bidirectional winding disk, and an electromagnetic clutch enable a single motor to assist hip extension and knee flexion in both legs. Furthermore, inertial measurement units (IMUs) installed on both legs predict walking gait position and gait cycle. In the control system, the host computer drives the motors through DSpace to drive the hip and knee joints, and the IMUs provide angle feedback to achieve normalized gait prediction. A designed dynamic model, PD iterative control, and fuzzy PID control are used to track the desired assistance curves for the hip and knee joints.

[0028] 2. Analyze the physiological structure of the human lower limb joints from an anatomical perspective, detailing their structural composition and motion patterns. By analyzing the kinematic and dynamic parameters of each lower limb joint during walking at different speeds, identify the assisting joints, assisting methods, and assisting timing, design joint active assist force curves, and propose a method for extracting motion intention. Based on the characteristics of the flexible exoskeleton's non-rigid rotational joints and the physiological structure of the hip and knee joints, a flexible lower limb multi-joint exoskeleton structure was designed incorporating a lasso drive mechanism. The exoskeleton drive module and flexible exoskeleton suit were studied, with a focus on the structural design and simulation optimization of the series elastic unit. The selection of some hardware was also completed. By combining an electromagnetic clutch with a bidirectional actuator, a single motor was used to provide power assistance to multiple joints. A PD-type iterative learning controller was developed to reduce periodic errors caused by individual wearer variability, thereby accurately tracking joint assist force curves. Plantar pressure sensors and IMU sensors were combined to enable real-time gait recognition and online prediction. Fuzzy logic was used to adjust PID parameters in real time, overcoming the limitations of traditional PID control methods that cannot be dynamically optimized.

[0029] Of course, any product implementing the present invention does not necessarily need to achieve all of the above advantages at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a frontal schematic diagram of a lower limb multi-joint exoskeleton robot worn on a human body;

[0032] Figure 2 This is a schematic diagram of the back of a lower limb multi-joint exoskeleton robot worn on a human body;

[0033] Figure 3 is a schematic diagram of the integrated wearable exoskeleton suit of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of the belt drive module of the integrated wearable exoskeleton suit of the present invention;

[0035] Figure 5 This is a schematic diagram of the structure of the thigh drive module of the integrated wearable exoskeleton suit of the present invention;

[0036] Figure 6 This is a schematic diagram of the structure of the calf drive module of the integrated wearable exoskeleton suit of the present invention;

[0037] Figure 7 is a schematic diagram of the drive device of the present invention;

[0038] Figure 8 1 is a schematic structural diagram of a sensor support frame according to the present invention;

[0039] Figure 9 This is a three-dimensional exploded view of the parallel elastic unit of the present invention;

[0040] Figure 10 This is a schematic diagram of the drive backplane structure of the present invention;

[0041] Figure 11 This is a schematic diagram of the gear shaft structure of the present invention;

[0042] Figure 12 is the torque curve of the left and right hip and knee joints;

[0043] Figure 13 The power curves of the left and right hip and knee joints are shown;

[0044] Figure 14 This is the auxiliary force curve of the hip and knee joints;

[0045] Figure 15 The mapping relationship between key gait positions and hip joint angles;

[0046] Figure 16 It is the dynamic model of the flexible lower limb multi-joint exoskeleton robot;

[0047] Figure 17 This is the principle diagram of the PD iterative control algorithm;

[0048] Figure 18 Fuzzy PID control principle diagram;

[0049] Figure 19 This is the overall control block diagram of the exoskeleton control method. DETAILED DESCRIPTION

[0050] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0051] like Figures 1-19 As shown, this embodiment provides a Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, including an integrated wearable exoskeleton suit 1, a drive device 2 and a Bowden cable 3; the shoulder strap part of the integrated wearable exoskeleton suit 1 is installed with the drive device 2, and the drive device 2 provides assistance to the integrated wearable exoskeleton suit 1 via the Bowden cable 3.

[0052] In this embodiment, the drive device 2 includes a motor 21, a motor support frame 22, a drive back plate 23, a Bowden cable reversing wheel 24, a sensor support frame 25, a reversing bevel gear set 26, an electromagnetic clutch 27, a parallel elastic unit 28, a gear shaft 29, and a bidirectional drive disk 210. The motor support frame 22 and the drive back plate 23 are mounted on the shoulder strap portion. The motor 21 is mounted on the motor support frame 22. Two drive back plates 23 are symmetrically mounted on both sides of the motor support frame 22. Each drive back plate 23 movably supports a gear shaft 29. The output shaft of the motor 21 is connected to the inner ends of the two gear shafts 29 through the reversing bevel gear set 26. The outer ends of the gear shafts 29 are connected to the bidirectional drive disk 210 through the electromagnetic clutch 27 and the parallel elastic unit 28. The motor support frame 22 can be fine-tuned on the drive back plate 23 to ensure optimal engagement and alignment of the reversing bevel gear set 26.

[0053] In this embodiment, the integrated wearable exoskeleton suit 1 includes a tights base 110, a belt drive module 130, a thigh drive module 140 and a calf drive module 150. The thigh drive module 140 is connected to the belt drive module 130 located above it and the calf drive module 150 located below it through module connecting nylon belts 120, and the bottom end of the calf drive module 150 is connected to the tights base 110; the drive device 2 realizes a single motor 21 to assist the hip joint extension and knee joint flexion in the left and right legs of the lower limbs through a reversing bevel gear set 26, an electromagnetic clutch 27 and a bidirectional winding disk 210.

[0054] In this embodiment, the belt drive module 130 is located at the waist of the human body 5, and uses nylon and nylon materials as the base 114; Velcro is sewn on the inside of the belt to ensure that it remains in a fixed position during exercise; during the power-assisting process, the power transmission belt transmits force to the iliac crest area of ​​the pelvis, so this area uses flexible material silicone 115 to disperse pressure and improve fit with the body; in order to increase the rigidity of the anchor point position and evenly distribute the force on the waist, nylon webbing is sewn on the base 114 of the tights, and the power transmission webbing is sewn in a "V" shape to transmit force to the opening of the belt; the nylon webbing 112 of the anchor point is sewn in a "V" shape. The belt is sewn in a shape and is provided with a first sleeve fixing device 111 and a Bowden cable reversing wheel 24 at a key position. The belt driving module 130 uses air eyelets 113 to fix both ends.

[0055] In this embodiment, the thigh drive module is located in the middle of the thigh of the human body 5 and uses the same base material as the waist belt drive module 130; a "V"-shaped low-temperature thermoplastic plate 122 is sewn on the side of the thigh drive module, and a Bowden wire end fixing device 123 is set at the top to ensure efficient transmission of tension; The low-temperature thermoplastic plate 122 is equipped with a second sleeve fixing device 123 and a Bowden cable reversing wheel 24 to reduce friction; the end Velcro is connected to the belt drive module 130, and the shape of the thigh drive module fits the thigh to prevent sliding when the motor 21 is driven.

[0056] In this embodiment, the calf driving module 150 is located in the middle of the calf of the human body 5, and adopts a nylon base 135, and is sewn with a low-temperature thermoplastic plate 132 to improve the anchor point rigidity and disperse the force.

[0057] In this embodiment, a main control box is installed above the driving device 2. The main control box includes a controller, a motor driver, a signal amplifier and a lithium battery. The main control box is connected to the driving device 2 through corresponding wires.

[0058] In this embodiment, the driving back plate 23 includes an upper back plate 231 and a lower back plate 232; the upper back plate 231 has a boss in the middle and recesses on both sides; the single-chip microcomputer and the signal amplifier are fixed to the upper back plate 231 by threaded connection, and the lithium battery is embedded in the groove of the upper back plate 231; the two sides of the lower back plate 232 are through holes for facilitating the motor 21, the motor support frame 22, the reversing bevel gear set 26, the electromagnetic clutch 27, the parallel elastic unit 28 and the bidirectional drive disk 210.

[0059] In this embodiment, the parallel elastic unit 28 adopts a modular structure and is composed of a pre-tightening bolt 282, a sleeve fixing block 284, a parallel spring 281 and a parallel spring tube 283; the initial pre-tightening force of the Bowden cable 3 is adjusted by the pre-tightening bolt 282. During the movement of the Bowden cable 3, the friction between the Bowden cable 3 and the Bowden cable tube drives the sleeve fixing block 284 to move, thereby compressing the parallel spring 281 in the parallel spring tube 283, thereby realizing a passive compliance function.

[0060] This embodiment also provides a method for controlling a Bowden cable-assisted flexible lower limb multi-joint exoskeleton, the method comprising the following steps:

[0061] S1. The driving device is placed on the back, and the shoulder straps are used to tightly fit the driving device and the back of the human body. The inertial measurement unit collects the rotation angle information of the thigh and hip joint to realize the recognition of human movement intention;

[0062] S2. A tension sensor collects tension information at the end of the Bowden cable. A dynamic equation for the flexible lower limb exoskeleton is established to derive the relationship between the joint assist value and the Bowden cable displacement. The desired assist force is converted into the desired displacement. A PD iterative learning controller is used to compensate for the position error to eliminate periodic errors.

[0063] S3. Finally, the displacement signal is used to dynamically control the motor through the fuzzy PID algorithm.

[0064] The exoskeleton control method uses a host computer system and an exoskeleton system. The host computer system includes a dspace host computer. The dspace host computer can obtain the hip joint motion angle collected by all inertial measurement units of the lower limb exoskeleton robot and the tension at the end of the Bowden cable collected by the tension sensor, and transmit them back to the host computer to realize force / displacement closed-loop control.

[0065] The exoskeleton system is a flexible lower limb multi-joint exoskeleton robot, including a drive device, a drive backplane, a main control box, a shoulder strap part, an integrated wearable exoskeleton suit, a tension sensor, and a Bowden cable. The mechanical structure other than the drive device and the main control box constitutes the exoskeleton. The main control box is equipped with a controller and an M3508 motor driver. The controller is also electrically connected to all the IMU inertial measurement units of the lower limb exoskeleton robot, and can obtain gait information collected by all the IMU inertial measurement units of the lower limb exoskeleton robot. The inertial measurement unit is installed in the middle of the left and right thighs; tension sensors are installed on the end fixing devices of the Bowden cables of the left and right hip and knee joints; the controller controls the operation of the corresponding motors in the drive device through the motor driver; the controller is loaded with hip and knee joint power assistance strategies;

[0066] In this embodiment, the motor model is M3508, the wire diameter of the Bowden cable double-slot winding reel is 45 mm, and the size of the entire drive device is 35*26*35 mm.

[0067] In this embodiment, the controller uses the Apollo STM32F407 core board of Zhengdian Atom.

[0068] In this embodiment, the inertial measurement unit uses a Jiuzhou Bluetooth attitude angle sensor, model HWT901B-CAN.

[0069] Through analysis Figure 14-15 The lower limb hip and knee joint torque and power curves are shown.

[0070]

[0071] During the gait cycle, there is an overlap between the right hip extension torque and the left knee flexion torque, indicating that both right hip extension and left knee flexion can be assisted simultaneously. To avoid interfering with normal knee motion, assistance should be terminated at the point of maximum knee flexion velocity, at which point right hip extension is not yet complete. Therefore, the gait cycle is defined from right toe-off to back-off, not from heel-strike. Figure 14 The results show that knee flexion power is primarily distributed between 48.5% and 73%, with a peak at 57.3%. Hip extension power is primarily distributed between 48.5% and 88%, with a peak at 66.6%. Because the combined power variation range for both joints is less than half of the gait cycle, the motor has ample time to reverse direction, providing assistance for left hip extension and right knee flexion through forward and reverse rotation.

[0072] by Figure 13-14 Based on the data, we designed Figure 15 The hip and knee joint assistance curves and the assistance curve expressions are used to turn on and off the electromagnetic clutch at specific times, so that a single motor can assist the hip joint extension and knee joint flexion of the left and right legs.

[0073] Gait recognition, such as Figure 15 The inertial measurement unit collects information on the rotation angle of the thigh hip joint. The plantar pressure sensor collects plantar pressure changes during the gait cycle, achieving the maximum hip joint extension angle to map the toe-off event and predict key gait positions. This not only meets the real-time control requirements of the exoskeleton system, but also reduces the number of sensors, optimizing the complexity and lightweight design of the system. The time difference between two adjacent maximum hip joint extension angles is used as the gait cycle, and a weighted prediction method is used to estimate the current gait cycle value.

[0074] Establish as Figure 16 The dynamic model shown is based on key parameters: the distance between the fixed point of the Bowden cable shell and the rotation center of the hip and knee joints, the angle between the corresponding connecting line and the horizontal line, the angle between the Bowden cable and the thigh and calf, the coordinate distance between the fixed point of the Bowden cable and the rotation center of the joint, the movement angle of the hip and knee joints, the distance between the anchor point of the exoskeleton suit and the joint, the length of the force arm between the rotation center of the joint and the Bowden cable, the change in the length of the Bowden cable caused by elastic deformation, and the current length of the Bowden cable corresponding to the hip and knee joints; the relationship between the Bowden cable displacement and the Bowden cable tension is obtained through stiffness measurement experiments.

[0075] The dynamic model uses key parameters: the distance between the fixed point of the Bowden cable shell and the rotation center of the hip and knee joints, the angle between the corresponding connecting line and the horizontal line, the angle between the Bowden cable and the thigh and calf, the coordinate distance between the fixed point of the Bowden cable and the rotation center of the joint, the movement angle of the hip and knee joints, the distance between the anchor point of the exoskeleton suit and the joint, the length of the force arm between the rotation center of the joint and the Bowden cable, the change in the length of the Bowden cable caused by elastic deformation, and the current length of the Bowden cable corresponding to the hip and knee joints; the relationship between the Bowden cable displacement and the Bowden cable tension is obtained through stiffness measurement experiments.

[0076] PD iterative learning controller, such as Figure 17 As shown in the figure, the target power assist value within the gait cycle is obtained through the inertial measurement unit module, and the error between it and the actual power assist value is calculated. After processing by the PD-type iterative learning controller, the desired motor position is output. Through iterative optimization, the motor position is gradually adjusted so that the actual power assist value approaches the expected value.

[0077] Fuzzy PID controller, such as Figure 18 As shown in the figure, PID parameters are adjusted in real time through fuzzy logic to improve the dynamic response capability of position tracking and overcome the limitation of traditional PID that cannot be dynamically optimized.

[0078] The angle information collected by all inertial measurement units and the Bowden cable tension collected by the tension sensor are sent to the DSpace host computer and the controller at the same time. Gait recognition is performed on the DSpace host computer to determine the current gait position. The DSpace host computer will identify the gait position and transmit it to the controller. The controller adopts the corresponding power assistance strategy based on the identified gait position, and realizes the tracking of the desired power assistance curve of the hip and knee joints through the designed dynamic model, PD iterative control and fuzzy PID control.

[0079] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot, characterized in that: The integrated wearable exoskeleton suit comprises a driving device and a Bowden cable; the driving device is installed on the shoulder strap of the integrated wearable exoskeleton suit, and the driving device provides power to the integrated wearable exoskeleton suit via the Bowden cable; The driving device includes a motor, a motor support frame, a driving back plate, a Bowden cable reversing wheel, a sensor support frame, a reversing bevel gear set, an electromagnetic clutch, a parallel elastic unit, a gear shaft and a bidirectional driving disk; the motor support frame and the driving back plate are installed on the shoulder strap part, the motor is installed on the motor support frame, two driving back plates are symmetrically installed on both sides of the motor support frame, each of the driving back plates is movably supported with a gear shaft, the output shaft of the motor is connected to the inner ends of the two gear shafts through the reversing bevel gear set, and the outer end of the gear shaft is connected to the bidirectional driving disk via the electromagnetic clutch and the parallel elastic unit.

2. The Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot according to claim 1, characterized in that: The integrated wearable exoskeleton suit includes a tights base, a belt drive module, a thigh drive module, and a calf drive module. The thigh drive module is connected to the belt drive module located above it and the calf drive module located below it through module connection nylon belts. The bottom end of the calf drive module is connected to the tights base. The drive device uses a reversing bevel gear set, an electromagnetic clutch, and a two-way winding disk to enable a single motor to assist the hip joint extension and knee joint flexion of the left and right legs.

3. The Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot according to claim 2, characterized in that: The belt drive module is located at the waist of the human body and is based on nylon and nylon materials; Velcro is sewn on the inside of the belt to ensure that it remains in a fixed position during exercise; during the power-assisting process, the power transmission belt transmits force to the iliac crest area of ​​the pelvis, so this area uses silicone flexible material to disperse pressure and improve fit with the body; in order to increase the rigidity of the anchor point and evenly distribute the force on the waist, nylon webbing is sewn on the base of the tights, and the power transmission webbing is sewn in a "V" shape to transmit force to the opening of the belt; the nylon webbing at the anchor point is sewn in a "V" shape. The belt is sewn in a molded manner and is equipped with a first sleeve fixing device and a Bowden line reversing wheel at a key position. The belt driving module is fixed at both ends with air eyelets.

4. The Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot according to claim 3, characterized in that: The thigh drive module is located in the middle of the human thigh and uses the same base material as the waist belt drive module; the thigh drive module is sewn with a "V"-shaped low-temperature thermoplastic plate on the side, and a Bowden wire end fixing device is set at the top to ensure efficient transmission of tension; the lower side is sewn with The low-temperature thermoplastic plate is equipped with a second sleeve fixing device and a Bowden cable reversing wheel to reduce friction; the end Velcro is connected to the belt drive module, and the shape of the thigh drive module fits the thigh to prevent sliding when the motor is driven.

5. The Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot according to claim 4, characterized in that: The calf drive module is located in the middle of the human calf, uses a nylon base, and is sewn with a low-temperature thermoplastic plate to increase the anchor point stiffness and disperse force.

6. The Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot according to claim 5, characterized in that: A main control box is installed above the driving device. The main control box includes a controller, a motor driver, a signal amplifier and a lithium battery. The main control box is connected to the driving device through corresponding wires.

7. The Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot according to claim 6, characterized in that: The drive backplane includes an upper backplane and a lower backplane; the upper backplane has a boss in the middle and depressions on both sides; the single-chip microcomputer and signal amplifier are fixed to the upper backplane by threaded connection, and the lithium battery is embedded in the groove of the upper backplane; the two sides of the lower backplane are through holes for the motor, motor support frame, reversing bevel gear set, electromagnetic clutch, parallel elastic unit and bidirectional drive disk.

8. The Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot according to claim 7, characterized in that: The parallel elastic unit adopts a modular structure and consists of a pre-tightening bolt, a sleeve fixing block, a parallel spring and a parallel spring tube. The initial pre-tightening force of the Bowden cable is adjusted by the pre-tightening bolt. During the movement of the Bowden cable, the friction between the Bowden cable and the Bowden cable tube drives the displacement of the sleeve fixing block, thereby compressing the parallel spring in the parallel spring tube to achieve a passive compliance function.

9. A Bowden cable-assisted flexible lower limb multi-joint exoskeleton control method, characterized in that: The equipment used in the control method includes a host computer system and the Bowden cable-assisted flexible lower limb multi-joint exoskeleton robot described in claim 8, wherein the host computer system includes a dspace host computer, and the dspace host computer can obtain the hip joint motion angle collected by all inertial measurement units of the lower limb exoskeleton robot and the tension at the end of the Bowden cable collected by the tension sensor, and transmit them back to the host computer to realize force / displacement closed-loop control; the controller in the main control box is electrically connected to all IMU inertial measurement units of the lower limb exoskeleton robot at the same time, and can obtain gait information collected by all IMU inertial measurement units of the lower limb exoskeleton robot, an inertial measurement unit is installed in the middle of the left and right thighs, and tension sensors are installed on the Bowden cable end fixing devices of the hip and knee joints of the left and right legs; the controller controls the operation of the corresponding motor in the drive device through the motor driver; The control method comprises the following steps: S1. The driving device is placed on the back, and the shoulder straps are used to tightly fit the driving device and the back of the human body. The inertial measurement unit collects the rotation angle information of the thigh and hip joint to realize the recognition of human movement intention; S2. A tension sensor collects tension information at the end of the Bowden cable. A dynamic equation for the flexible lower limb exoskeleton is established to derive the relationship between the joint assist value and the Bowden cable displacement. The desired assist force is converted into the desired displacement. A PD iterative learning controller is used to compensate for the position error to eliminate periodic errors. S3. Finally, the displacement signal is used to dynamically control the motor through the fuzzy PID algorithm.

10. The Bowden cable-assisted flexible lower limb multi-joint exoskeleton control method according to claim 9, characterized in that: During the gait cycle, there is an overlapping area between the right hip extension torque and the left knee flexion torque. To avoid interfering with normal knee motion, power assistance should be terminated when the knee flexion velocity is at its maximum. At this time, right hip extension has not yet been completed. The gait cycle is defined as from right toe lift-off to right toe lift-off, not heel strike. Because the sum of the power change ranges of the two joints is less than half of the gait cycle, the motor has ample time to perform reversing operations, achieving power assistance for left hip extension and right knee flexion through forward and reverse rotation. The electromagnetic clutch is switched on and off at specific times, enabling a single motor to assist in hip extension and knee flexion of the left and right legs; The inertial measurement unit collects information on the rotation angle of the thigh hip joint. The plantar pressure sensor collects plantar pressure changes during the gait cycle, achieving the maximum hip joint extension angle to map the toe-off event and predict key gait positions. The time difference between two adjacent maximum hip joint extension angles is used as the gait cycle, and a weighted prediction method is used to estimate the current gait cycle value using the previous three gait cycle values. The angle information collected by all inertial measurement units and the Bowden cable tension collected by the tension sensor are sent to the DSpace host computer and the controller at the same time. Gait recognition is performed on the DSpace host computer to determine the current gait position. The DSpace host computer will identify the gait position and transmit it to the controller. The controller adopts the corresponding power assistance strategy based on the identified gait position, and realizes the tracking of the desired power assistance curve of the hip and knee joints through the designed dynamic model, PD iterative control and fuzzy PID control.

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