Pneumatic-electric hybrid driven flexible exoskeleton robot system and control method thereof

Abstract

The invention belongs to the technical field of bionic exoskeletons, and particularly relates to a pneumatic-electric hybrid driven flexible exoskeleton robot system and a control method thereof.The pneumatic-electric hybrid driven flexible exoskeleton robot system comprises a flexible exoskeleton body which is bound to the lower limbs of the human body and comprises a plurality of pneumatic muscles arranged around the shanks and Bowden cables located between the pneumatic muscles; a power source module; the control center is configured to dynamically switch a pneumatic driving mode and a motor driving mode according to the rehabilitation stage and the environment scene of the wearer; the sensor module is used for collecting motion data in real time; the control center is based on sensor data, a bionic multi-muscle self-adaptive control strategy and a force-position mixed control strategy are adopted, accurate assistance of multi-dimensional movement of the ankle joint is achieved, and dual protection is formed through a pneumatic muscle constant-pressure locking mechanism and a Bowden cable active force unloading mechanism. According to the device, through pneumatic-electric hybrid driving, an intelligent control strategy and innovative protection design, the problems that traditional exoskeleton driving is single, the degree of freedom is insufficient, and safety is low are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of bionic exoskeletons, and in particular relates to a gas-electric hybrid-driven flexible exoskeleton robot system and a control method thereof. Background Art

[0002] In the field of modern medical rehabilitation, exoskeleton technology, as a cutting-edge auxiliary means, is gradually changing the wearer's rehabilitation treatment model. Traditional exoskeletons and new flexible exoskeletons are the main research directions in this field. Each has unique characteristics and application scenarios, but also has some obvious drawbacks.

[0003] Characteristics and limitations of traditional exoskeletons: Traditional exoskeletons are generally constructed of metal materials, which give the exoskeleton strong support and structural rigidity, and can provide strong support for the user in some specific scenarios. However, its heavy weight has become a key factor restricting the user's freedom of movement, making the user's movements subject to many restrictions after wearing it, making it difficult to perform flexible movements. In addition, traditional exoskeletons lack sufficient adaptability and cannot fit the natural shape of the human body well during wearing. This not only brings great inconvenience to the wearer, but also easily causes skin friction, increasing discomfort when wearing it.

[0004] In recent years, new flexible exoskeletons have emerged due to their design features using flexible materials. This design allows the exoskeleton to better fit the natural shape of the human body, greatly reducing the burden on the wearer and significantly improving wearing comfort, while also reducing skin friction and discomfort when wearing. In the field of clinical rehabilitation, flexible exoskeletons have demonstrated greater flexibility and adaptability, and can more effectively provide wearers with comfortable and personalized rehabilitation training, better meeting the wearer's diverse needs during the rehabilitation process. However, there are still some problems with the drive method and structural design of flexible exoskeletons.

[0005] Currently, flexible exoskeleton robots are primarily driven by pneumatic artificial muscle and motor-Bowden cable. While pneumatic artificial muscle can simulate the contraction mechanism of human muscles, providing smooth movement similar to natural muscle, it also possesses natural cushioning capabilities, effectively adapting to sudden external force shocks and reducing rigid impacts on joints. However, it requires an air compressor or high-pressure gas tank, which severely limits the exoskeleton's range of motion and makes it unsuitable for outdoor use. Motor-Bowden cable drive, on the other hand, relies solely on batteries and is more suitable for outdoor or mobile operations. Furthermore, the motor facilitates precise control of torque and displacement. However, when the load changes, cable stretching introduces positional errors, which require compensation through force sensors or closed-loop control. Furthermore, the Bowden cable requires preload to prevent loosening, which results in additional energy loss.

[0006] Existing flexible exoskeletons have relatively simple structures, and most can only provide rehabilitation for a specific stage of the wearer's joint impairment, resulting in a narrow range of applications. Furthermore, existing flexible exoskeletons generally suffer from limited degrees of freedom. For example, they typically only assist with ankle plantar flexion and dorsiflexion, with limited support for ankle inversion and eversion, making them difficult to meet the wearer's multi-dimensional motion needs in real-world applications. Summary of the Invention

[0007] In response to the above-mentioned prior art, the present invention provides a gas-electric hybrid-driven flexible exoskeleton robot system and a control method thereof, which can realize convenient production, transportation, on-site assembly and use of modules.

[0008] In order to solve the above technical problems, the present invention proposes a gas-electric hybrid drive flexible exoskeleton robot system, comprising:

[0009] The flexible exoskeleton is strapped to the lower limb of the human body and includes multiple pneumatic muscles arranged around the calf, a Bowden cable located between the pneumatic muscles, a universal footrest that mimics the structure of a human ankle, flexible fixing straps located above the footrest and between the calf and knee joint, an overall fixing structure located above the knee joint, and a fixing housing for the pneumatic muscles and Bowden cable.

[0010] The power source module includes an air pump and a power supply, which are used to drive the pneumatic muscle and the Bowden cable respectively;

[0011] A control center configured to dynamically switch between pneumatic drive mode and motor drive mode according to the wearer's rehabilitation stage and environmental scenario;

[0012] Sensor module, including force sensor and angle sensor, used to collect motion data in real time;

[0013] The control center adopts a bionic multi-muscle adaptive control strategy and a force-position hybrid control strategy based on sensor data to achieve precise assistance of multi-dimensional movement of the ankle joint, and forms dual protection through a pneumatic muscle constant pressure locking mechanism and a Bowden cable active unloading mechanism.

[0014] Preferably, the number of the pneumatic muscles is four, which are symmetrically arranged around the calf and are respectively connected to the air pump through a high-speed switching valve; the Bowden cable is located between adjacent pneumatic muscles and is driven by a motor.

[0015] Preferably, the control center enables the pneumatic drive mode in the early and middle stages of the wearer's rehabilitation, and realizes plantar flexion, dorsiflexion, inversion and eversion movements of the ankle joint by adjusting the air pressure of the pneumatic muscles; in the late stage of rehabilitation and outdoor scenes, it switches to the motor drive mode, turns off the air pump and locks the pneumatic muscle pressure, and the Bowden cable performs active assistance.

[0016] Preferably, in the pneumatic drive mode, the control center generates a high-speed switch valve control signal according to a preset gait angle curve, and dynamically adjusts the air pressure distribution through a multi-muscle coordination mechanism; in the motor drive mode, the control center adopts an impedance control strategy based on force sensor data to adjust the Bowden cable tension in real time.

[0017] Preferably, the double protection includes:

[0018] Pneumatic muscle constant pressure locking mechanism, when gait imbalance is detected, maintains the preset air pressure of the pneumatic muscle to form a passive protective layer;

[0019] The Bowden cable's active unloading mechanism switches to impedance control mode in the event of sudden impact or abnormal gait, reducing the Bowden cable load.

[0020] A method for controlling the system according to claim 1, comprising the following steps:

[0021] S1: Select the driving mode according to the rehabilitation stage and environmental scenario;

[0022] S2: In pneumatic drive mode, bionic multi-muscle control signals are generated through sensor data, and the air pressure of the pneumatic muscles is adjusted to achieve multi-dimensional motion assistance;

[0023] S3: In motor drive mode, the Bowden cable is driven by a force-position hybrid control strategy, and the load status is monitored in real time to trigger the protection mechanism;

[0024] S4: When gait abnormality is detected, the pneumatic muscle constant pressure lock and the Bowden cable active force unloading are activated synchronously.

[0025] Preferably, the control strategy of the pneumatic drive mode includes:

[0026] Calculate the deviation between the expected angle and the actual angle based on the ankle joint angle data collected by the angle sensor;

[0027] The coordinated contraction instructions of the pneumatic muscles are generated through an adaptive algorithm to dynamically adjust the opening of the high-speed switching valve.

[0028] Preferably, the control strategy of the motor drive mode includes:

[0029] Based on the data from the foot force sensor and angle sensor, the motor target displacement is generated using position closed-loop control;

[0030] Combined with the Bowden cable tension data, the error caused by load changes is eliminated through a dynamic compensation algorithm.

[0031] Preferably, the triggering conditions of the protection mechanism include:

[0032] The ankle inversion angle exceeds the preset threshold;

[0033] The angular velocity changes suddenly or the Bowden cable load exceeds the safe range.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The pneumatic-electric hybrid drive flexible exoskeleton system provided by the present invention can adapt to the wearer's needs at all stages, before, during, and after rehabilitation. In the early stages of rehabilitation, when the wearer is unable to actively move, passive training is achieved through pneumatic muscle drive; in the middle stages of rehabilitation, the power assistance intensity is dynamically adjusted using an adaptive control strategy; and in the later stages, it switches to motor drive mode to support outdoor walking training. One set of equipment can meet the full cycle of rehabilitation treatment, reducing equipment replacement costs and improving rehabilitation continuity.

[0036] (2) The system achieves seamless integration between indoor and outdoor environments by dynamically switching drive modes. Indoor scenarios, the system uses a pneumatic drive mode, leveraging the flexibility and natural cushioning capacity of pneumatic muscles to provide safe and stable rehabilitation training. Outdoor scenarios switch to a motor-Bowden cable drive mode, relying on battery power to achieve lightweight, high-precision torque control, adapting to complex terrain and mobility requirements.

[0037] (3) Through the coordinated layout of four pneumatic muscles and Bowden cables, the system can accurately control the plantar flexion, dorsiflexion, inversion, and eversion of the ankle joint, covering movement dimensions that are difficult to achieve with traditional exoskeletons. For example, the inversion / eversion direction is driven by a specific combination of pneumatic muscles, significantly improving the comprehensiveness of rehabilitation training and meeting the wearer's actual movement needs.

[0038] (4) When a gait imbalance is detected (such as an excessive inversion angle or a sudden change in angular velocity), the pneumatic muscles maintain the preset air pressure, forming a nonlinear stiffness protection layer, and quickly generate antagonistic torque through a tendon-like damping effect to prevent excessive twisting of the joint. Under sudden impact or abnormal load, the system switches to impedance control mode, actively reducing the tension of the Bowden cable and triggering the secondary protection of the pneumatic muscles, forming an "active + passive" dual protection, significantly reducing the risk of falls.

[0039] (5) The gas-electric hybrid drive mode allocates energy based on the needs of the scene. Indoors, it relies on the air pump for efficient energy supply, while outdoor operation switches to electric motor drive to reduce air source dependence and extend the device's endurance. The two drive modes complement each other, taking into account energy efficiency and performance, and improving the overall practicality of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0041] Figure 2 is a three-dimensional diagram of the flexible exoskeleton robot system of the present invention;

[0042] Figure 3This is a front view of the flexible exoskeleton robot system of the present invention;

[0043] Figure 4 This is a schematic diagram of the dorsiflexion working state (No. 2 and No. 3 pneumatic muscles working) in the present invention;

[0044] Figure 5 Schematic diagram of the plantar flexion working state (No. 1 and No. 4 pneumatic muscles working) in the present invention;

[0045] Figure 6 This is a schematic diagram of the inversion working state (No. 1 and No. 2 pneumatic muscles working) of the present invention;

[0046] Figure 7 This is a schematic diagram of the present invention in the eversion working state (No. 3 and No. 4 pneumatic muscles working);

[0047] Figure 8 Schematic diagram of the plantar flexion working state (Bowden cable No. 1 is in a stretched state) in the present invention;

[0048] Figure 9 This is a schematic diagram of the dorsiflexion working state (the second Bowden cable is in a stretched state) of the present invention;

[0049] Figure 10 This is the control strategy of the gas-electric hybrid flexible exoskeleton in the present invention

[0050] Figure 11 This is the control process of the gas-electric hybrid flexible exoskeleton in the present invention. DETAILED DESCRIPTION

[0051] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention in any way.

[0052] like Figure 1-3 As shown, the present invention proposes a gas-electric hybrid driven flexible exoskeleton robot system, comprising: a gas-electric hybrid driven flexible exoskeleton robot system 1 that is strapped to the human calf, a power source 2 for providing power to the gas-electric hybrid flexible exoskeleton robot system, and a control center 3 for the entire exoskeleton robot.

[0053] The flexible exoskeleton robot system 1, which is strapped to the human calf and driven by a pneumatic-electric hybrid, includes four pneumatic muscles surrounding the calf: pneumatic muscle No. 1 1.1.1, pneumatic muscle No. 2 1.1.2, pneumatic muscle No. 3 1.1.3, and pneumatic muscle No. 4 1.1.4; Bowden cable No. 1 1.2.1 and Bowden cable No. 2 1.2.2 located between pneumatic muscle No. 2 1.1.2 and pneumatic muscle No. 3 1.1.3, and between pneumatic muscle No. 1 1.1.1 and pneumatic muscle No. 4 1.1.4, respectively; a universal footrest 1.3 with a bionic human ankle structure, a flexible fixing strap 1.4.1 located on the upper part of the footrest, and a flexible fixing strap 1.4.2 located between the calf and the knee joint; an overall fixing structure 1.5 located on the upper part of the knee joint; and a fixing shell 1.6 for the pneumatic muscles and Bowden cables.

[0054] The power source 2 includes an air pump for providing power to the artificial pneumatic muscle when driven by air pressure and a power source for providing power when driven by a motor.

[0055] Before using the pneumatic-electric hybrid-driven flexible exoskeleton robot system, all system components must be properly installed. The flexible exoskeleton robot assembly 1, which is strapped to the wearer's calf, must be securely and comfortably secured to the wearer's calf using a flexible securing strap 1.4.1 located above the footrest, a flexible securing strap 1.4.2 located between the calf and knee joint, and an integral securing structure 1.5 located above the knee joint. Ensure that pneumatic muscles 1.1.1, 2, 3, and 4, as well as Bowden cables 1.2.1 and 2, surrounding the calf, are in proper working order, and that the universal footrest 1.3, which mimics the structure of a human foot and ankle, fits the wearer's foot properly. Connect the power source 2, ensuring the proper operation and stable connection of the air pump and power supply as needed. Ensure that all circuits in the exoskeleton robot's control center 3 are correctly connected and functioning properly.

[0056] During the wearer's early and mid-term rehabilitation process, this pneumatic-electric hybrid flexible exoskeleton robot system mainly achieves rehabilitation treatment by driving pneumatic muscles with air pressure. During this period, the wearer is unable to actively train or has weak muscles during training and is unable to walk. Pneumatic drive drives the pneumatic muscles and, by simulating the human muscle synergistic recruitment mechanism, helps the wearer activate muscles and achieve multi-dimensional flexible rehabilitation exercise training. Taking the right foot as an example: First, we establish the desired angle curve of the human walking gait. Based on the desired angle curve, angle control processing is performed. The control target of the high-speed switching valve is generated according to the bionic multi-muscle adaptive control strategy. Secondly, the high-speed switching valve controls the input air pressure of different pneumatic muscles, enabling the wearer to perform multi-dimensional rehabilitation exercises of plantar flexion, dorsiflexion, inversion, and eversion. At the same time, the angle sensor on the foot collects angle data and uploads it to the single-chip microcomputer for processing. The processing results are then processed again by the bionic multi-muscle control strategy and finally fed back to the angle control for adjustment, achieving a rehabilitation effect with real-time adjustment, dynamic assistance, and precise control. During rehabilitation exercises, angle sensors installed on the foot collect real-time angle data and upload this data to the microcontroller. The microcontroller performs preliminary processing on the data before further processing using a bionic multi-muscle control strategy. The processed results are fed back to the angle control module, which adjusts the control target of the high-speed switching valve, thereby adjusting the input pressure to the pneumatic muscles in real time. This cycle enables real-time adjustment, dynamic assistance, and precise control of the wearer's rehabilitation exercises, ensuring the safety and effectiveness of rehabilitation training.

[0057] Figure 4-9 Different pneumatic muscles work to achieve assistance in different directions. Red represents the pneumatic muscles in working state, and green represents the non-working state. In the flexible exoskeleton robot system driven by a hybrid gas-electric drive, the combination of different pneumatic muscles in working state provides multi-directional assistance to the wearer's ankle joint, meeting the diverse needs of rehabilitation training. Red represents the pneumatic muscles in working state, and green represents the non-working state. The specific working modes are as follows:

[0058] Dorsiflexion: During dorsiflexion, pneumatic muscles 2 and 3 are active (red), while pneumatic muscles 1 and 4 are inactive (green). At this point, pneumatic muscles 2 and 3 contract, pulling the calf and foot upward to achieve dorsiflexion. This coordinated contraction mimics the body's natural muscle movement pattern, providing a smooth assist for the wearer's dorsiflexion rehabilitation training, effectively strengthening the corresponding muscle groups and restoring ankle dorsiflexion function.

[0059] Plantar flexion: When plantar flexion is achieved, pneumatic muscles 1 and 4 are activated (red), while pneumatic muscles 2 and 3 are deactivated (green). The contraction of pneumatic muscles 1 and 4 drives the calf and foot downward, completing the plantar flexion. This power-assisted mode helps strengthen the wearer's plantar flexion muscles and improve ankle plantar flexion function, which is crucial for enhancing the wearer's walking and standing stability.

[0060] Inversion: Inversion is achieved by the active pneumatic muscles 1 and 2 (red), while pneumatic muscles 3 and 4 are inactive (green). The combined force of pneumatic muscles 1 and 2 causes the foot to roll inward, achieving inversion. This is crucial for restoring ankle inversion function and enhancing foot control, better simulating normal human movement patterns and improving rehabilitation training effectiveness.

[0061] Eversion: Eversion is achieved by activating pneumatic muscles 3 and 4 (red), while pneumatic muscles 1 and 2 are inactive (green). Contraction of pneumatic muscles 3 and 4 rotates the foot outward, completing the eversion movement. This power-assisted method helps improve ankle eversion function, enhancing ankle flexibility and stability in various directions of movement, meeting the wearer's diverse athletic needs in real life.

[0062] When the wearer enters the later stages of rehabilitation and outdoor walking assistance, the system dynamically reconfigures the drive mode and safety protection mechanisms, achieving a seamless transition from precise indoor rehabilitation to walking assistance in complex outdoor environments. Once the wearer regains basic walking ability, the system automatically switches to the motor-driven Bowden cable drive mode: the air pump is shut down and the high-speed switching valve is locked, maintaining the pneumatic muscle at a personalized preset air pressure, forming a passive protective layer with nonlinear stiffness characteristics. This air pressure is dynamically optimized based on the wearer's weight, muscle strength, and balance ability. When the ankle inversion angle exceeds a certain set value or the angular velocity suddenly changes, the pneumatic muscle's tendon-like damping effect quickly reacts to generate an antagonistic torque, providing preliminary fall protection. Simultaneously, the motor takes over the active assistance task via the Bowden cable drive system. The foot angle sensor collects data in real time, preprocesses the acquired raw data, and uploads the preprocessed data to the microcontroller. The control center utilizes a force-position hybrid control architecture. The microcontroller performs position control based on the current angle. An adaptive flexible control strategy assists with dynamic adjustments. Based on the force-position hybrid control strategy, the motor target point is generated. The motor executes the output, pulling the Bowden cable to initiate assistance. Foot force sensors collect data and upload it to the microcontroller for flexible force control adjustments. Dynamic adjustments complete this process, achieving flexible assistance for the wearer. During this process, force sensors also monitor the Bowden cable load in real time. If a sudden impact or gait abnormality is detected, the system immediately switches to impedance control mode to actively unload the force. This simultaneously triggers pneumatic muscle preload pressure for secondary joint protection, creating a dual anti-fall mechanism of "active control + passive elasticity." This provides a safe and reliable outdoor mobility solution for the wearer's post-stroke rehabilitation.

[0063] While the wearer is assisting with walking outdoors, the force sensor monitors the load status of the Bowden cable in real time. Upon detecting a sudden impact or abnormal gait, the system immediately switches to impedance control mode to actively unload the force, preventing injury to the wearer due to abnormal forces. Simultaneously, the pneumatic muscle preload pressure is triggered to implement secondary joint protection, further enhancing fall protection. This dual "active control + passive elasticity" fall protection mechanism ensures the wearer's safety while assisting with walking in complex outdoor environments.

[0064] This device solves the problems of traditional exoskeleton's single drive, insufficient degrees of freedom, and low safety through gas-electric hybrid drive, intelligent control strategy and innovative protection design. It provides rehabilitation wearers with a full-cycle, multi-scenario, and highly safe ankle joint assistance solution, with significant clinical value and application prospects.

[0065] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can make many improvements and changes without departing from the purpose of the present invention, which are all protected by the present invention.

Claims

1. A flexible exoskeleton robot system driven by a gas-electric hybrid drive, characterized in that: include: The flexible exoskeleton is strapped to the lower limb of the human body and includes multiple pneumatic muscles arranged around the calf, a Bowden cable located between the pneumatic muscles, a universal footrest that mimics the structure of a human ankle, flexible fixing straps located above the footrest and between the calf and knee joint, an overall fixing structure located above the knee joint, and a fixing housing for the pneumatic muscles and Bowden cable. The power source module includes an air pump and a power supply, which are used to drive the pneumatic muscle and the Bowden cable respectively; A control center configured to dynamically switch between pneumatic drive mode and motor drive mode according to the wearer's rehabilitation stage and environmental scenario; Sensor module, including force sensor and angle sensor, used to collect motion data in real time; The control center adopts a bionic multi-muscle adaptive control strategy and a force-position hybrid control strategy based on sensor data to achieve precise assistance of multi-dimensional movement of the ankle joint, and forms dual protection through a pneumatic muscle constant pressure locking mechanism and a Bowden cable active unloading mechanism.

2. The system according to claim 1, wherein: There are four pneumatic muscles, which are symmetrically arranged around the calf and are respectively connected to the air pump through a high-speed switching valve; the Bowden cable is located between adjacent pneumatic muscles and is driven by a motor.

3. The system according to claim 1, wherein: The control center enables the pneumatic drive mode in the early and middle stages of the wearer's rehabilitation, and realizes plantar flexion, dorsiflexion, inversion and eversion movements of the ankle joint by adjusting the air pressure of the pneumatic muscles; in the late stages of rehabilitation and outdoor scenes, it switches to the motor drive mode, turns off the air pump and locks the pneumatic muscle pressure, and the Bowden cable performs active assistance.

4. The system according to claim 3, characterized in that In the pneumatic drive mode, the control center generates a high-speed switch valve control signal according to a preset gait angle curve, and dynamically adjusts the air pressure distribution through a multi-muscle coordination mechanism; in the motor drive mode, the control center adopts an impedance control strategy based on force sensor data to adjust the Bowden cable tension in real time.

5. The system according to claim 1, wherein: The double protection includes: Pneumatic muscle constant pressure locking mechanism, when gait imbalance is detected, maintains the preset air pressure of the pneumatic muscle to form a passive protective layer; The Bowden cable's active unloading mechanism switches to impedance control mode in the event of sudden impact or abnormal gait, reducing the Bowden cable load.

6. A control method for the system according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Select the driving mode according to the rehabilitation stage and environmental scenario; S2: In pneumatic drive mode, bionic multi-muscle control signals are generated through sensor data, and the air pressure of the pneumatic muscles is adjusted to achieve multi-dimensional motion assistance; S3: In motor drive mode, the Bowden cable is driven by a force-position hybrid control strategy, and the load status is monitored in real time to trigger the protection mechanism; S4: When gait abnormality is detected, the pneumatic muscle constant pressure lock and the Bowden cable active force unloading are activated synchronously.

7. The method according to claim 6, characterized in that The control strategy of the pneumatic drive mode includes: Calculate the deviation between the expected angle and the actual angle based on the ankle joint angle data collected by the angle sensor; The coordinated contraction instructions of the pneumatic muscles are generated through an adaptive algorithm to dynamically adjust the opening of the high-speed switching valve.

8. The method according to claim 6, characterized in that The control strategy of the motor drive mode includes: Based on the foot force sensor data, position closed-loop control is used to generate the motor target displacement; Combined with the Bowden cable tension data, the error caused by load changes is eliminated through a dynamic compensation algorithm.

9. The method according to claim 6, characterized in that The triggering conditions of the protection mechanism include: The ankle inversion angle exceeds the preset threshold; The angular velocity changes suddenly or the Bowden cable load exceeds the safe range.

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