Single-drive flexible lower limb exoskeleton based on parallel time-sharing auxiliary strategy

Abstract

The application discloses a single-drive flexible lower limb assisting exoskeleton based on a parallel time-sharing auxiliary strategy, which comprises a backpack, a wearable flexible clothes, a power supply, assisting boots, a Bowden cable, a control system, a driving system and a sensing system; the sensing system comprises a flexible foot bottom force sensor arranged at the bottom of the assisting boots and a tension sensor hung on the heel of the assisting boots; the sensing system is electrically connected with the control system; the power supply, the control system and the driving system are integrated in the backpack; the backpack is connected with the wearable flexible clothes and worn on the human body; the assisting boots are worn on the feet; the control system is electrically connected with the driving system; and the driving system is connected with the tension sensor through the Bowden cable.The application can provide the ankle joint assistance and the propulsion of the lower leg in walking of the human body in time-sharing mode, reduce the energy consumption of the user, help the lower limb dysfunction correct and improve the walking gait, provide the torque to restore the balance when the human body is about to fall, and has good safety and application prospect.

Description

Technical Field

[0001] This invention relates to the field of flexible wearable robot technology, and to a single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy, and particularly to a single-drive flexible wearable lower limb assistive exoskeleton robot based on a parallel time-sharing assistance strategy. Background Technology

[0002] Wearable exoskeleton robots have been widely used in assisting people with walking, rehabilitation training, and other scenarios. Currently, wearable exoskeleton robots can generally be divided into two types: rigid exoskeletons and flexible exoskeletons. Most exoskeletons currently use a rigid structure, typically including a rigid load-bearing structure and powerful actuators. Their working principle is that when a person walks, the actuators transmit force to the ground along links to reduce the load on the body and energy consumption. However, for those who still have the ability to walk after nerve damage, such as most stroke patients recovering, these robots may not always be the best choice for restoring normal gait function due to their high inertia and joint alignment problems.

[0003] With the continuous development of exoskeleton robot technology, the shortcomings of rigid exoskeleton robots can now be solved by flexible exoskeleton robots. Due to the advantages of flexible materials such as textiles and elastomers, such as light weight and high flexibility, and the ability to provide a way to maintain shape and compliantly exchange force with the human body, flexible wearable exoskeletons made from these materials have shown great potential in fields such as medical rehabilitation.

[0004] During human walking, approximately 46% of the positive mechanical power is contributed by ankle-foot flexion. Therefore, lower limb exoskeletons that provide auxiliary torque at the ankle can better assist human walking. Furthermore, considering the continuity of human gait—ankle-foot flexion is immediately followed by a single-leg swing phase—a single-drive structure can be designed to assist the lower leg in swinging forward after assisting ankle flexion. By improving the robot's structure, time-sharing assistance to the ankle and lower leg is achieved, not only assisting human movement but also avoiding increasing the number of drives and preventing the robot from becoming too heavy and affecting its wearability. Compared to rigid exoskeleton robots, flexible wearable exoskeleton robots have the advantages of being lightweight, having low inertia, and being easy to wear, providing users with better assisted walking capabilities.

[0005] However, it's worth noting that current flexible wearable exoskeletons lack consideration for human-machine interaction and safety during assisted walking. Firstly, flexible exoskeleton robots need to be in close contact with the human body, so human-machine interaction design directly impacts user comfort and experience. Human-machine interaction in flexible exoskeleton systems can also be used to achieve real-time perception and feedback of user movements. By using sensors to monitor user movement, the exoskeleton can adjust and respond accordingly to the user's intentions, thus achieving more precise and flexible movement assistance. Secondly, current flexible exoskeleton robots focus on providing better assistance capabilities, neglecting the safety of the movement process. Exoskeleton robots should have the ability to avoid danger and react to unexpected safety issues during assistance.

[0006] Therefore, developing a flexible wearable exoskeleton that provides good human-computer interaction feedback while ensuring safety during movement is of great practical significance. Summary of the Invention

[0007] Due to the aforementioned deficiencies in existing technologies, this invention provides a flexible wearable exoskeleton with good human-computer interaction feedback and the ability to ensure safety during movement. Specifically, it is a single-drive flexible lower limb wearable exoskeleton robot that can provide excellent assistance capabilities in different time periods, is highly safe, lightweight and portable, and overcomes the shortcomings of existing flexible wearable exoskeletons that lack consideration for human-computer interaction feedback and safety during assisted walking.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assist strategy includes a backpack, wearable flexible clothing, power supply, assistive boots, Bowden cable, control system, drive system, and sensing system.

[0010] The sensing system includes a flexible plantar force sensor and a tension sensor. The flexible plantar force sensor and the tension sensor are electrically connected to the control system via a data cable. The flexible plantar force sensor is arranged at the bottom of the power boot, and the tension sensor is attached to the pull tab at the heel of the power boot. The tension sensor measures the tension between the Bowden cable and the power boot, i.e., the human-machine interaction force, and transmits the measured tension data to the control system via the tension sensor data cable. The flexible plantar force sensor measures the pressure between the sole of the foot and the ground, and transmits the measured pressure data to the control system via the flexible plantar force sensor data cable.

[0011] The power supply, control system, and drive system are integrated into the backpack (worn on the body to provide assistance). The backpack is connected to a wearable flexible garment and worn on the body. The assistive boots (used to receive the auxiliary traction force transmitted by the Bowden cable) are worn on the feet. The power supply provides power to the control system and drive system. The control system and drive system are electrically connected. The drive system is connected to the tension sensor via the Bowden cable (which transmits the auxiliary force generated by the drive system).

[0012] The control system obtains the pressure between the user's foot and the ground in real time through a flexible foot force sensor, thereby determining the user's current center of gravity. If the center of gravity deviates from the set range, the control system determines a stabilization plan and sends a signal to the drive system according to the stabilization plan. The drive system then operates to drive the Bowden cable to assist the user in restoring balance.

[0013] The control system sends a signal to the drive system according to the assist scheme. The drive system then pulls the user's ankle joint to rotate via the Bowden cable. At this time, the tension sensor sends the measured tension data to the control system in real time.

[0014] This invention can provide ankle joint assistance and lower leg propulsion for human walking in a time-sharing manner, reducing the user's energy consumption. It can also provide certain rehabilitation effects for people with lower limb dysfunction, correcting and improving their walking gait. This invention also takes into account the safety of the assistance process. The sensing system can detect the body's center of gravity and provide torque to restore the body's balance when the person is about to lean forward or backward and fall, ensuring the user's safety.

[0015] This invention relates to a single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy. Made of flexible materials, it is lightweight, requires minimal user load, and offers a superior user experience. Its rational structural design provides excellent ankle joint assistance without increasing motor drive capacity. Through structural optimization and improved drive mechanism, it also assists the lower leg. The sensing, drive, and control systems work together to achieve real-time perception and feedback of user movements. It not only assists in walking but also ensures safety during the exoskeleton robot's assistance process. Flexible plantar force sensors measure the pressure and distribution between the foot and the ground. This data allows the control system to analyze the user's center of gravity. When the center of gravity shifts, the control system can control a brushless DC motor to generate torque to restore the center of gravity, preventing accidents. This invention shows promising application prospects.

[0016] As a preferred technical solution:

[0017] As described above, a single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy has heat dissipation holes at the rear of the backpack (to dissipate the heat generated by the power supply, control system and drive system during operation, and to prevent the system from malfunctioning due to overheating). The backpack can be 3D printed using resin material.

[0018] The control system includes a main control board, peripheral interfaces, and a data protocol converter. The main control board is electrically connected to the peripheral interfaces and the data protocol converter. The peripheral interfaces are electrically connected to a flexible foot force sensor and a tension sensor. The main control board receives and processes the human-computer interaction force and pressure data measured by the sensing system, generates control commands to the drive system, and enables the drive system to generate appropriate auxiliary torque. Specifically, it receives and analyzes the tension and pressure data measured by the sensing system, controls the drive system to generate corresponding torque to assist human movement, and can monitor the user's center of gravity. When the user's center of gravity deviates from the normal range, the control system can control the drive system to immediately generate corresponding actions to prevent the user from leaning forward or falling.

[0019] Specifically, the main control board can use the LattePanda Alpha single-board computer, powered by 5V; the peripheral interface can use a USB expansion dock to provide interfaces for the data lines of the tension sensor and the flexible plantar force sensor; the data protocol converter can use the Kvaser Leafs Light v2, which can convert the USB serial communication protocol to the CAN communication protocol; the main control board and the data protocol converter are fixed inside the backpack, and the peripheral interface is fixed outside the backpack.

[0020] The drive system includes a driver and a brushless DC motor. The driver is electrically connected to a data protocol converter and to the brushless DC motor. The brushless DC motor is electrically connected to a Bowden cable. The driver receives control signals from the control system, adjusts the output voltage, and controls the brushless DC motor to rotate accordingly, generating torque.

[0021] Specifically, the driver can be an Elmo Solo Whistle servo driver, and the brushless DC motor can be a Maxon 600W EC 90 high torque motor. The drive system assists the ankle and lower leg in a time-sharing manner. First, it assists the ankle joint to flex, at which time the rear Bowden cable is tightened and the front Bowden cable is relaxed. When the assisted foot leaves the ground, the assistance to the ankle joint ends, the brushless DC motor reverses, causing the rear Bowden cable to relax and the front Bowden cable to tighten, assisting the lower leg to move forward.

[0022] As described above, in a single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assist strategy, the tension sensor has hooks at both ends. One hook is attached to the pull bar at the heel of the assistive boot, and the other hook is tied and fixed to the Bowden cable.

[0023] As described above, a single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy includes a Bowden cable comprising a left front Bowden cable, a left rear Bowden cable, a right front Bowden cable, and a right rear Bowden cable.

[0024] As described above, a single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy includes a wearable flexible suit comprising a back strap, a waist belt, Velcro, and straps (for receiving forward propulsion force transmitted by Bowden cables);

[0025] The shoulder straps are equipped with adjustable buckles, allowing the length to be adjusted to fit the user's chest circumference.

[0026] The belt is worn around the user's waist and has an adjustable buckle at the end, which can be freely adjusted in length and fixed to the waist, so that the wearable flexible clothing fits the user's body to the greatest extent and improves comfort.

[0027] The Velcro is worn on the user's thigh and can be freely adjusted for tightness. It is fixed with pulleys at the front and back for the left front Bowden cable, right front Bowden cable, left rear Bowden cable or right rear Bowden cable to pass freely through, which guides the movement of the Bowden cable and avoids affecting the torque transmitted by the Bowden cable.

[0028] The strap is worn on the user's calf and its tightness can be freely adjusted. At the rear, there is a pulley for the left or right rear Bowden cable to pass through freely (to guide the movement path of the Bowden cable). At the front, there is a pull ring for securing the left or right rear Bowden cable (to receive the forward thrust transmitted by the Bowden cable). The torque generated by the DC brushless motor transmitted by the left or right front Bowden cable can drive the calf forward through the pull ring, converting the motor torque into a propulsive force that drives the calf forward.

[0029] As described above, in a single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assist strategy, the flexible plantar force sensor is embedded in the insole of the assistive boot and placed inside the boot together with the insole. It can measure the interaction force between the sole of the foot and the ground, as well as the distribution of the plantar force.

[0030] As described above, in a single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy, one end of the Bowden cable is fixed inside the shaft of a brushless DC motor, and the Bowden cables on the same side are wound around the shaft of the brushless DC motor in opposite directions. When the motor rotates in one direction, one of the Bowden cables will tighten and the other Bowden cable will loosen, and vice versa, thereby generating pulling force and propulsive force on the user's ankle joint and lower leg respectively in a time-sharing manner.

[0031] Bowden cables come in two types: a Bowden cable that assists the ankle from the rear and a Bowden cable that assists the lower leg from the front. The Bowden cable that assists the ankle from the rear is connected to a DC brushless motor and a tension sensor at both ends, respectively. It passes through pulleys fixed to the thigh Velcro strap and the back of the strap, which can transmit the auxiliary torque generated by the DC brushless motor to the assistive boot to assist the user's ankle flexion. The Bowden cable that assists the lower leg from the front is connected to a DC brushless motor and a pull ring at both ends, and passes through pulleys fixed to the thigh Velcro strap, which can convert the torque generated by the DC brushless motor into a propulsive force to drive the lower leg forward, assisting the user's lower leg forward.

[0032] The power supply uses 60V and 5V rechargeable lithium batteries respectively, which are electrically connected to the control system, drive system and sensing system through wires to provide them with the power required for normal operation. The 60V rechargeable lithium battery can provide power to the sensing system, and the 5V rechargeable lithium battery can provide power to the control system.

[0033] The drive system provides traction for ankle rotation and propulsion for lower leg movement via Bowden cables. Ankle assistance is achieved by transmitting the torque generated by the DC brushless motor to the user's ankle through the Bowden cables and hooks, providing traction. Lower leg assistance is achieved by transmitting the torque generated by the DC brushless motor to a strap on the lower leg through the Bowden cables. The traction force on the strap is converted into propulsion force for the lower leg, assisting the user's forward movement when taking a step.

[0034] The above technical solution is only one feasible technical solution of the present invention. The scope of protection of the present invention is not limited thereto. Those skilled in the art can reasonably adjust the specific design according to actual needs.

[0035] The above invention has the following advantages or beneficial effects:

[0036] (1) The single-drive flexible lower limb assistive exoskeleton based on parallel time-sharing assist strategy of the present invention is mainly made of flexible materials. Compared with rigid exoskeleton robots, its mass is greatly reduced, which helps to reduce the user's load. Flexible materials have better fit and adaptability than rigid materials, making it more comfortable for users to wear.

[0037] (2) The single-drive flexible lower limb assistive exoskeleton based on the parallel time-sharing assist strategy of the present invention provides good ankle joint assist capability and does not increase motor drive. Through structural optimization and drive method improvement, it also achieves lower leg assistance. It adopts a method of driving both ankle joints and lower legs simultaneously with a single motor. The Bowden cables on both sides do not interfere with each other. The Bowden cables on the same side are wound around the shaft of the DC brushless motor in opposite ways. This drive method does not restrict human movement and provides users with better walking ability.

[0038] (3) The single-drive flexible lower limb assistive exoskeleton based on parallel time-sharing assist strategy of the present invention incorporates a sensing system. A tension sensor is used to measure the human-machine interaction force. The control system will adaptively adjust the output torque of the DC brushless motor according to the magnitude of the interaction force, so as to realize real-time perception and feedback of user actions, thereby improving the comfort and accuracy of exoskeleton robot assistance.

[0039] (4) The single-drive flexible lower limb assistive exoskeleton based on the parallel time-sharing assist strategy of the present invention ensures the safety of the exoskeleton robot during the assist process. It uses a flexible foot force sensor to measure the pressure and distribution between the foot and the ground. The data can enable the control system to analyze the center of gravity of the human body. When the center of gravity of the human body shifts, the control system can control the DC brushless motor to generate torque to restore the center of gravity of the human body and avoid danger. It has good application prospects. Attached Figure Description

[0040] The invention, its features, shape, and advantages will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Like reference numerals denote like parts throughout the drawings. The drawings are not drawn to scale; their focus is on illustrating the gist of the invention.

[0041] Figure 1 This is a three-dimensional structural diagram of the single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy of the present invention.

[0042] Figure 2 This is a diagram showing the inside of the backpack;

[0043] Figure 3 This is a schematic diagram of the leg portion of the single-drive flexible lower limb assistive exoskeleton of the present invention;

[0044] Figure 4 This is a system structure diagram of the single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy of the present invention;

[0045] Figure 5 A schematic diagram of a power boot;

[0046] Figure 6 The working state and human gait cycle diagram of a single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy;

[0047] The components are as follows: 1-Backpack; 2-Wearable flexible clothing; 3-Power supply; 4-Assistive boots; 5-Bowden cable; 6-Control system; 7-Drive system; 8-Sensing system; 9-Heat dissipation vents; 10-Shoulder straps; 11-Waist belt; 12-Hook and loop fasteners; 13-Pulleys; 14-Boots; 15-Pull ring; 16-Main control board; 17-Peripheral interface; 18-Data protocol converter; 19-Driver; 20-DC brushless motor; 21-Tension sensor; 22-Flexible plantar force sensor; 23-Adjustable buckle; 24-Hook; 25-Tension sensor data cable; 26-Flexible plantar force sensor data cable; 27-Strap. Detailed Implementation

[0048] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but these are not intended to limit the scope of the invention.

[0049] Example 1

[0050] A single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy, such as Figures 1-6 As shown, it includes: backpack 1, wearable flexible clothing 2, power supply 3, assistive boots 4, Bowden cable 5, control system 6, drive system 7, and sensing system 8.

[0051] The backpack 1 is 3D printed from resin material and has ventilation holes 9 on the outside to prevent excessive heat generated by the power supply 3, control system 6, and drive system 7 during normal operation, which could lead to system malfunction. The backpack 1 connects to the wearable flexible suit 2 and can be worn on the shoulder via shoulder straps 10. The shoulder straps have adjustable buckles 23, allowing for length adjustment according to chest circumference. To further conform to the human body, a waist belt 11 and adjustable buckles 23 are added at the waist, allowing users to adjust the length to maximize comfort. The wearable flexible suit 2 also includes Velcro 12 and straps 27 for the lower limbs. The Velcro is worn on the thighs and has pulleys 13 fixed at the front and back to restrain the movement of the Bowden cable 5. The Velcro 12 can also be adjusted in length according to user needs. The strap 27 is threaded onto the lower leg, with a pulley 13 fixed behind it to constrain the movement trajectory of the Bowden cable 5. A pull ring is fixed in front, connected to the Bowden cable on the front side, to receive the auxiliary torque generated by the brushless DC motor transmitted by the Bowden cable and convert it into a propulsive force to move the lower leg forward.

[0052] The power supply 3 consists of two parts: a 60V output rechargeable lithium battery for powering the drive system 7 and a 5V output rechargeable lithium battery for powering the main control system 6. Both are installed and fixed inside the backpack 1.

[0053] The assistive boot 4 is a specially designed boot, consisting of a regular boot 14 worn on the foot and a pull ring 15 fixed to the heel. The pull ring 15 is connected to the boot 14 through a metal washer and is the main force point. It is supported by the auxiliary torque generated by the DC brushless motor 20 transmitted by the Bowden cable 5, thereby driving the movement of the human ankle joint.

[0054] The control system 6 mainly includes a main control board 16 and a peripheral interface 17. The main control board 16 is installed and fixed inside the backpack 1, and its operation is powered by a 5V rechargeable lithium battery. The peripheral interface 17 is connected to the USB interface of the main control board as an extension of the USB interface, and is used to connect the data line 25 of the tension sensor and the data line 26 of the flexible foot force sensor. One end of the data protocol converter 18 is connected to the USB interface of the main control board 16, and the other end is connected to the driver, which can convert USB serial communication into CAN communication. The main control board 16 can receive and analyze the human-machine interaction force data measured by the tension sensor 21, and then send control commands to the driver 16 through the data protocol converter 18, so that the driver outputs the corresponding voltage to drive the DC brushless motor to rotate and generate torque. At the same time, the main control board 16 can also receive the pressure data measured by the flexible foot force sensor, calculate the center of gravity of the human body according to the pressure distribution, and when the center of gravity of the human body shifts, the main control board 16 can immediately generate control commands to control the DC brushless motor 20 to rotate accordingly, so as to restore the balance of the human body by applying auxiliary torque to the human body and avoid accidents.

[0055] The drive system 8 includes a driver 19 and a brushless DC motor 20. The driver 19 is electrically connected to the power supply 3 via wires and is powered by a 60V rechargeable lithium battery. It is connected to the main control board 16 via a data protocol converter 18. The output port of the driver 19 is connected to the brushless DC motor 20 via wires. After receiving control commands from the main control board 16, it can change the output voltage to control the brushless DC motor 20 to rotate accordingly, thereby generating the required torque. Four Bowden cables 5 are wound inside the shaft of the brushless DC motor 20. The four Bowden cables are divided into two groups, each distributed on one side of the human body. In the Bowden cables on the same side, the front and back Bowden cables are wound in opposite directions. This ensures that when the brushless DC motor 20 rotates in one direction, one side of the Bowden cable is taut, transferring the torque generated by the motor to the corresponding force point, while the other side of the Bowden cable is slack and does not exert any force on the human body, and vice versa. Bowden cables on different sides at the same location (front or back) move in the same direction. When the DC brushless motor 20 rotates to one side, the Bowden cable 5 on that side releases more free length due to the motor rotation, and the Bowden cable 5 becomes slack. Conversely, the Bowden cable 5 on the other side tightens its length due to the motor rotation, and will exert a force on the force point through the Bowden cable to assist the movement of the human body.

[0056] The sensing system 22 mainly consists of four sensors, including one tension sensor 21 and one flexible plantar force sensor 22 on each side. The tension sensor 21 has hooks 24 at both ends; one end connects to the Bowden cable 5, and the other end connects to the boot 14 via a pull ring 15. The side is connected to the main controller 16 via a tension sensor data cable. During the assist phase, the Bowden cable 5 transmits the torque generated by the DC brushless motor 20, pulling the ankle joint to rotate. At this time, the tension sensor measures the tension between the Bowden cable 5 and the assist boot 4 and transmits the measured data to the main control board (16) for data analysis. The flexible plantar force sensor 22 is embedded in the insole of the boot 14, but the flexible plantar force sensor data line 26 is brought out and connected to the main control board 16 through the peripheral interface 17. When the user walks normally, the left and right flexible plantar force sensors will measure the pressure between the sole of the foot and the ground in real time and transmit the measured pressure data to the main control board 16. The main control board will analyze the human body's center of gravity based on the different pressure levels of different parts of the sole. When the center of gravity deviates from the normal range, the main controller 16 will generate a command to control the DC brushless motor 20 to generate torque to help the human body restore balance.

[0057] The working principle of this invention is as follows:

[0058] like Figure 6 As shown, the operation of this invention is divided into four states: the swing phase, the free support phase, the ankle-assisted support phase, and the lower leg-assisted forward movement phase. Analyzing one side, the gait cycles of the left and right legs are consistent, as are their movement patterns, and therefore the states they pass through are also consistent. However, there is a time difference in the overall gait cycles of the left and right legs. During the swing phase of the left leg, the right leg is in the support phase, and vice versa. Therefore, it is only necessary to analyze the case where one leg steps forward first; the other side is completely identical. To facilitate understanding of the working principle of this invention, Bowden cables are categorized according to their orientation as follows: left anterior Bowden cable (the Bowden cable in front of the left thigh, with similar naming conventions for subsequent Bowden cables), left posterior Bowden cable, right anterior Bowden cable, right posterior Bowden cable, and left Bowden cable (a collective term for the left anterior and left posterior Bowden cables), and right Bowden cable (a collective term for the right anterior and right posterior Bowden cables).

[0059] The analysis focuses on the scenario where the right leg steps forward first. Before the user begins walking, the system is powered on and ready to operate. At this time, the brushless DC motor has no output torque, but the sensors have already started working. The data measured by the tension sensor does not affect the user's state because there is no control signal output. However, the data measured by the flexible plantar force sensor is received and analyzed by the main control board. When the system determines that the user's center of gravity is deviating from the safe range due to an impending fall, the main control board immediately sends a control command to make the brushless DC motor generate torque to help the user regain balance.

[0060] When the user begins walking, the main control board first controls the DC brushless motor to rotate clockwise according to a preset reference trajectory, generating auxiliary torque. Due to the motor's rotation, the right rear Bowden cable tightens while the left Bowden cable releases, causing the right rear Bowden cable to taut. This tension applies force to the heel of the assist boot via a hook, thereby rotating the right ankle joint and assisting the user's right leg. Meanwhile, the left rear Bowden cable slacks. Simultaneously, because the right rear Bowden cable is taut due to the motor's rotation, the right front Bowden cable remains slack and does not provide assistance to the lower leg; this stage is the ankle joint support phase. During this process, the tension sensor on the right side measures the tension between the right rear Bowden cable and the right assist boot in real time and transmits the measured data to the main control board via the tension sensor data cable. After receiving the data, the main control board analyzes and processes it, making adjustments to the preset reference trajectory and generating control signals to control the rotation of the DC brushless motor. This ensures that the torque generated by the motor is more realistic, improving the accuracy of the assistance and the comfort of the human-machine interface.

[0061] Once the right foot leaves the ground, the assist ends, and the system enters a brief pendulum phase. During this time, the main control board controls the DC geared motor to rotate counterclockwise. The right rear Bowden cable gradually slackens, while the left rear Bowden cable gradually slackens, returning to its initial state. Simultaneously, because the right rear Bowden cable gradually slackens, the right front Bowden cable gradually slackens, also returning to its initial state. Throughout this process, since the Bowden cables are transitioning to their initial states, no additional force is applied to the ankle or calf; this phase offers no assistive effect.

[0062] When the right foot begins to swing forward, the system enters the lower leg assisted forward movement stage. At this time, according to the preset reference trajectory, the main control board will control the DC brushless motor to rotate counterclockwise. The right rear Bowden cable changes from the initial state to a slack state, and the right front Bowden cable changes from the initial state to a gradually taut state. At this time, the right front Bowden cable will transmit the torque generated by the motor to the right lower leg. The right strap receives the torque transmitted by the right front Bowden cable through the pull ring and converts it into propulsion force to help the lower leg move forward.

[0063] When the right foot has swung forward and is about to land, the system enters the pendulum phase again. At this time, the main control board will control the DC brushless motor to rotate clockwise, so that the right rear and right front Bowden cables are tightened and relaxed respectively, returning to the initial state. During this process, the Bowden cables have no effect on the right ankle joint and lower leg.

[0064] Before the right foot re-landes, the left ankle joint needs to rotate to propel the body forward. The system enters the ankle joint assisted support phase. At this time, the main control board first controls the DC brushless motor to rotate counter-clockwise according to a preset reference trajectory, generating auxiliary torque. Due to the motor's rotation, the left rear Bowden cable tightens while the right Bowden cable releases. Therefore, the left rear Bowden cable becomes taut, applying tension to the heel of the boot via a hook on the assist boot, thereby rotating the left ankle joint and assisting the user's left leg in walking. Meanwhile, the right Bowden cable relaxes. As the left ankle joint rotates, the user's right leg touches the ground. The left ankle joint still needs to rotate for a while before leaving the ground; the assist does not stop during this process. Simultaneously, due to the tension of the left rear Bowden cable, the left front Bowden cable relaxes, exerting no force on the left calf. During the left ankle joint assistance process, the tension sensor on the left side measures the tension between the left rear Bowden cable and the left assist boot in real time and transmits the measured data to the main control board via the tension sensor data cable. After receiving the data, the main control board analyzes and processes it, makes changes on the preset reference trajectory, and generates control signals to control the rotation of the brushless DC motor. This makes the torque generated by the motor more in line with the actual situation, which can improve the accuracy of the assistance and the comfort of human-machine interaction.

[0065] Then the left foot leaves the ground, the assistance to the left leg ends, and the system enters a brief pendulum phase. The main control board begins to control the motor to return to zero. The left rear Bowden cable will gradually loosen, and the right Bowden cable will gradually tighten, returning to the initial state. This process will not exert any force on the ankle joint and lower leg.

[0066] When the left foot begins to swing forward, the system enters the lower leg assisted forward movement stage. The main control board will control the motor to rotate accordingly to assist the left lower leg in moving forward. Since the gait cycle is consistent in subsequent walking, the subsequent assistance process for the left leg is the same as that for the right leg. The DC brushless motor rotates in the opposite direction, so the process will not be described in detail.

[0067] Throughout the walking process, the flexible plantar pressure sensor remains operational, measuring the contact force between the foot and the ground in real time. This data is transmitted to the main control board via a data cable. The main control board receives and processes the data to calculate the user's center of gravity. If the main control board detects that the calculated center of gravity deviates from the normal walking range, it determines that the user is about to tilt and is at risk of falling. Therefore, the main control board immediately controls the brushless DC motor to rotate accordingly to assist the user in regaining balance. Normal assistance resumes once the user has regained balance. The anti-fall system has the highest control priority; regardless of the system's current state, once activated, it will terminate all assistance to prevent the user's center of gravity from shifting.

[0068] Those skilled in the art should understand that variations can be implemented by combining existing technology with the above embodiments, which will not be elaborated here. Such variations do not affect the essence of the present invention, and will not be elaborated here either.

[0069] The preferred 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 the devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy, characterized in that: This includes backpacks, wearable flexible clothing, power supplies, power boots, Bowden cables, control systems, drive systems, and sensing systems. The sensing system includes a flexible plantar force sensor and a tension sensor. The flexible plantar force sensor and the tension sensor are electrically connected to the control system via a data cable. The flexible plantar force sensor is arranged at the bottom of the power boot, and the tension sensor is attached to the pull tab at the heel of the power boot. The power supply, control system, and drive system are integrated in the backpack, which is connected to the wearable flexible garment and worn on the human body. The assistive boots are worn on the feet. The power supply provides power to the control system and drive system. The control system and drive system are electrically connected. The drive system is connected to the tension sensor via Bowden cable. The drive system includes a driver and a brushless DC motor. The driver is electrically connected to a data protocol converter and to the brushless DC motor. The brushless DC motor is electrically connected to Bowden cables. The Bowden cables include a front left Bowden cable, a rear left Bowden cable, a front right Bowden cable, and a rear right Bowden cable. One end of each Bowden cable is fixed inside the shaft of the brushless DC motor, and the Bowden cables on the same side are wound around the shaft of the brushless DC motor in opposite directions. The control system obtains the pressure between the user's foot and the ground in real time through a flexible foot force sensor, thereby determining the user's current center of gravity. If the center of gravity deviates from the set range, the control system determines a stabilization plan and sends a signal to the drive system according to the stabilization plan. The drive system then operates to drive the Bowden cable to assist the user in restoring balance. The drive system assists the ankle and lower leg in a time-sharing manner. First, it assists the ankle joint to flex, at which time the rear Bowden cable is tightened and the front Bowden cable is relaxed. When the assisted foot leaves the ground, the assistance to the ankle joint ends, the DC brushless motor reverses, causing the rear Bowden cable to relax and the front Bowden cable to tighten, and the assisted lower leg to move forward. The control system sends a signal to the drive system according to the assist scheme. The drive system then pulls the user's ankle joint to rotate via the Bowden cable. At this time, the tension sensor sends the measured tension data to the control system in real time.

2. The single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy according to claim 1, characterized in that, The backpack has ventilation holes at the rear. The control system includes a main control board, a peripheral interface, and a data protocol converter. The main control board is electrically connected to the peripheral interface and the data protocol converter, and the peripheral interface is electrically connected to a flexible foot force sensor and a tension sensor.

3. The single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy according to claim 1, characterized in that, The tension sensor has hooks at both ends. One hook is attached to the pull bar at the heel of the power boot, and the other hook is tied and fixed to the Bowden cable.

4. The single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy according to claim 1, characterized in that, The wearable flexible garment includes suspenders, a waist belt, Velcro, and straps; The shoulder strap is equipped with an adjustable buckle; The belt is worn around the user's waist and has an adjustable buckle at the end; The Velcro strap is worn on the user's thigh, and pulleys are fixed at the front and back for the left front Bowden cable, right front Bowden cable, left rear Bowden cable, or right rear Bowden cable to pass freely. The strap is worn on the user's calf, with a pulley fixed at the back for the left or right rear Bowden cable to pass freely through, and a pull ring fixed at the front for securing the left or right rear Bowden cable.

5. A single-drive flexible lower limb assistive exoskeleton based on a parallel time-sharing assistance strategy according to claim 1, characterized in that, The flexible foot force sensor is embedded in the insole of the power boot.

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