Active two-degree-of-freedom ankle-foot exoskeleton device and method based on synergistic control

Abstract

The application relates to a synergistically controlled active two-degree-of-freedom ankle-foot exoskeleton device and method, which comprises a leg fixing assembly, a foot fixing assembly supporting the wearer's foot sole, a foot-leg connecting assembly connected between the two, a driving assembly enabling the fixed rod to rotate around a first hinge structural member in the sagittal plane relative to the foot-leg connecting assembly and enabling the foot-leg connecting assembly to rotate around a second hinge structural member in the coronal plane relative to the foot support, a signal acquisition module for acquiring three-dimensional posture data and plantar pressure information of the foot and lower leg in real time, and a control module for controlling the driving assembly to work according to the acquired signals, so that the fixed rod can rotate around the first hinge structural member in the sagittal plane relative to the foot-leg connecting assembly, and the foot-leg connecting assembly can rotate around the second hinge structural member in the coronal plane relative to the foot support, thereby realizing active assistance of two degrees of freedom of the ankle joint dorsiflexion / planter flexion and inversion / eversion, and providing active intervention for two types of movement disorders of foot drop and foot inversion / eversion.

Description

Technical Field

[0001] This invention relates to the field of rehabilitation assistive robot technology, specifically to an active dual-degree-of-freedom ankle-foot exoskeleton device and method based on collaborative control. Background Technology

[0002] The ankle joint is one of the most important weight-bearing joints in human walking, undertaking the coordinated movement of two main degrees of freedom in the sagittal and coronal planes during the normal gait cycle.

[0003] Patients with neuromuscular diseases such as stroke, spinal cord injury, and peripheral neuropathy often have ankle joint movement dysfunction, among which foot drop and foot inversion are the most typical symptoms: foot drop is mainly manifested as insufficient ankle dorsiflexion, resulting in the forefoot striking the ground and the toes dragging when walking; foot inversion is manifested as coronal plane control disorder, resulting in deviation of the walking trajectory (circular gait). Both seriously affect the patient's walking safety and gait quality.

[0004] Traditional ankle-foot orthoses are usually rigid or semi-rigid passive structures that can only fix the ankle joint through mechanical restraint to prevent foot drop and forefoot landing, but cannot provide active assistance, nor can they achieve dynamic response to gait phase, and are particularly lacking in control of coronal plane degrees of freedom.

[0005] To overcome the limitations of passive orthotics, active ankle-foot exoskeletons have gradually become a research hotspot.

[0006] Existing active ankle-foot exoskeletons typically use electric motors or pneumatic drives, combined with plantar pressure sensors and inertial measurement units (IMUs) to collect gait information, thereby achieving active assistive control of the ankle joint.

[0007] However, the existing technologies mentioned above have the following shortcomings: most existing ankle and foot exoskeleton devices only actively control a single degree of freedom in the sagittal plane (dorsiflexion / plantarflexion), and lack the ability to actively intervene in the degree of freedom in the coronal plane (inversion / eversion).

[0008] In clinical practice, foot inversion and foot drop often occur together. Controlling only the sagittal plane degrees of freedom cannot effectively improve the circumduction gait and is difficult to meet the actual rehabilitation needs of patients.

[0009] Some existing devices rely solely on plantar pressure sensors for gait phase determination, lacking the fusion and utilization of three-dimensional posture data of the foot and lower leg. This limits the accuracy of gait phase recognition and makes it difficult to accurately decouple the motion angles of the sagittal and coronal planes, resulting in insufficient real-time performance and precision of control commands.

[0010] Existing devices typically rely on current sensor data for feedback control, failing to anticipate the height of the toes off the ground and thus unable to trigger timely compensation control before the toes touch the ground, posing a tripping risk and requiring improved safety.

[0011] Existing devices generally design control strategies for the sagittal and coronal planes independently, failing to establish a collaborative control model between the two degrees of freedom. This results in mutual interference between the control of the two degrees of freedom in complex gait scenarios, leading to poor gait naturalness.

[0012] In view of this, it is necessary to provide an active dual-degree-of-freedom ankle-foot exoskeleton device to achieve coordinated active intervention on foot drop and foot inversion, so as to overcome the above-mentioned shortcomings of the prior art. Summary of the Invention

[0013] Therefore, it is necessary to provide an active dual-degree-of-freedom ankle-foot exoskeleton device and method based on collaborative control, addressing the problem that existing ankle-foot exoskeleton devices only provide unidirectional control and cannot coordinate.

[0014] An active dual-degree-of-freedom ankle-foot exoskeleton device based on collaborative control, comprising: A leg fixation assembly includes a fixing rod and a tensioning mechanism disposed on one side of the fixing rod, wherein the fixing rod is fixed to the wearer's lower leg by the tensioning mechanism; A foot fixation component includes a foot support and a foot fixation component fixed to one end of the foot support. The foot support is used to support the wearer's foot, and the foot fixation component is located near the center of the wearer's sole and is fixed to the wearer's foot by a strap. The foot and leg connection assembly has a connecting rod and a first hinge structure and a second hinge structure located at both ends of the connecting rod. One end of the connecting rod is connected to one end of the fixed rod through the first hinge structure, and the other end is connected to the end of the foot support near the wearer's heel through the second hinge structure. The drive assembly includes a first drive motor and a second drive member. The first drive motor is used to drive the first hinge structure to rotate the fixed rod relative to the foot-leg connection assembly in the sagittal plane around the first hinge structure. The second drive member is used to drive the second hinge structure to rotate the foot-leg connection assembly relative to the foot support member in the coronal plane around the second hinge structure. The signal acquisition module includes an inertial measurement unit disposed on the instep and lower leg and a pressure sensor array distributed on the sole of the foot. The inertial measurement unit is used to acquire three-dimensional posture data of the foot and lower leg in real time, and the pressure sensor array is used to acquire sole pressure information in real time. The control module is electrically connected to the signal acquisition module and is used to control the operation of the drive component based on the three-dimensional posture data of the foot and lower leg and the plantar pressure information acquired by the signal acquisition module, at least to make the fixed rod rotate around the first hinge structure relative to the foot and leg connection component.

[0015] In one preferred embodiment, the second driving member is a second drive motor controlled by the control module, which drives the foot-leg connection assembly to rotate relative to the foot support member around the second hinge structure.

[0016] In one preferred embodiment, the control module obtains the first rotation angle of the fixed rod relative to the foot-leg connection component around the first hinge structure and the second rotation angle of the foot-leg connection component relative to the foot support component around the second hinge structure based on the three-dimensional posture data of the foot and lower leg and the plantar pressure information collected by the signal acquisition module and the gait phase recognition algorithm, and controls the first drive motor and the second drive motor to drive according to the corresponding rotation angle.

[0017] In one preferred embodiment, the second drive motor is disposed on one side of the second hinge structure to drive the second hinge structure to rotate.

[0018] In one preferred embodiment, the first drive motor is disposed on one side of the first hinge structure to drive the first hinge structure to rotate.

[0019] In one preferred embodiment, the inertial measurement unit includes a three-axis accelerometer and a three-axis gyroscope.

[0020] In one preferred embodiment, the second drive member is a second damping member, which controls the rotation of the foot-leg connection assembly relative to the foot support member around the second hinge structure member by manual adjustment.

[0021] The device described above is driven independently by a first drive motor and a second drive component, enabling the fixed rod to rotate relative to the foot-leg connection assembly in the sagittal plane around the first hinge structure, and the foot-leg connection assembly to rotate relative to the foot support component in the coronal plane around the second hinge structure. This allows for active assistance of two degrees of freedom of ankle joint dorsiflexion / plantar flexion and inversion / eversion on a single device, providing active intervention for two types of movement disorders: foot drop and foot inversion / eversion.

[0022] A control method for an active dual-degree-of-freedom ankle-foot exoskeleton device, used in the aforementioned active dual-degree-of-freedom ankle-foot exoskeleton device, characterized in that the method includes: The signal acquisition module acquires three-dimensional posture data of the foot and lower leg, as well as plantar pressure information. A foot rotation matrix is ​​formed within the constructed spatial geometric mapping model. and lower leg rotation matrix The relative foot-leg rotation matrix is ​​obtained. ; Based on the relative rotation matrix of the foot and leg The decoupling process obtains the first free angle of the fixed rod relative to the foot and leg connecting assembly in the sagittal plane around the first hinge structure, and the second free angle of the foot and leg connecting assembly relative to the foot support member around the second hinge structure. When the first free angle exceeds the corresponding angle threshold, the first drive motor is triggered to control the first free angle. When the second free angle exceeds the angle threshold, the second drive motor is triggered to control the second free angle. The acquired three-dimensional posture data of the foot and lower leg, as well as the plantar pressure information, are imported into the constructed gait recognition model to obtain the wearer's current gait information; Based on the high intervention model, it is determined whether the first free angle of the wearer in the current gait information exceeds the first safety threshold. If it does, the control amount of the first drive motor driving the first hinge structure is compensated. Based on the circling compensation model, it is determined whether the wearer's movement trajectory in the current gait information exceeds the error threshold. If it does, the control amount of the second drive motor driving the second hinge structure is compensated.

[0023] In one preferred embodiment, the foot-to-leg rotation matrix relative to the lower leg satisfy:

[0024] in, For the rotation matrix of the lower leg The transpose of .

[0025] In one preferred embodiment, the first free angle satisfies:

[0026] The second free angle satisfies:

[0027] in, As the first free angle, This is the second free angle.

[0028] In one preferred embodiment, the step of importing the acquired three-dimensional posture data of the foot and lower leg, as well as the plantar pressure information, into the constructed gait recognition model to obtain the wearer's current gait information includes: The gait recognition model uses a gait phase recognition algorithm based on a hidden Markov model or a finite state machine. Based on the acquired three-dimensional posture data of the foot and lower leg and plantar pressure information, it obtains four mutually exclusive gait information of the wearer. The gait information includes heel strike, full foot support, toe lift, and swing phase.

[0029] In one preferred embodiment, the height-based intervention model includes a height detection unit, a height prediction unit, and a height compensation unit, wherein the height detection unit satisfies:

[0030] in, For toe height detection, The velocity of the wearer's lower leg in the vertical direction. The distance from the center of the wearer's ankle joint to the toes. The angle of the wearer's lower leg relative to the vertical line. The dorsiflexion / plantarflexion angle, For foot structural parameters, For the current moment, The starting time; The height prediction unit satisfies:

[0031] in, Predicting height for the toes For toe height detection, The rate of change of toe height at the current moment. Let be the second derivative of the current toe height; The height compensation unit satisfies:

[0032] in, The minimum height threshold, To compensate for the gain, To compensate for the torque exerted by the first drive motor on the first hinge structure.

[0033] In one preferred embodiment, the method further includes: Based on the collaborative control model, the wearer's foot inversion or eversion angle in the coronal plane is controlled according to the current toe detection height. The collaborative control model satisfies:

[0034] in, The target control angle for the coronal plane. The neutral posture angle of the foot (the baseline eversion / inversion angle during normal walking). For the cooperative control gain coefficient, Toe height is measured.

[0035] In one preferred embodiment, the circle-based compensation model satisfies:

[0036] in, For composite compensation torque, The first adjustment coefficient, This is the second adjustment coefficient. For gravity compensation, The foot trajectory error in the coronal plane. satisfy:

[0037] The For the coronal reference trajectory, For the actual trajectory in the coronal plane, gravity compensation term satisfy:

[0038] The The total mass of the foot. It is the acceleration due to gravity. This is the distance from the foot's center of mass to the ankle joint's axis of rotation. The angle of inclination of the foot relative to the direction of gravity.

[0039] In one preferred embodiment, the method further includes: Impedance control of joint motion is performed based on a damping control model, which satisfies the following:

[0040] in, This is the equivalent inertia of the joint. Joint angular acceleration, The damping coefficient is... The joint angular velocity, This is the stiffness coefficient. This refers to the actual angle of the joint. From the perspective of the target, For external torque, This refers to the motor torque.

[0041] The method described above in this invention constructs a spatial geometric mapping model to form foot rotation matrices. and calf rotation matrix Then, the relative foot and leg rotation matrix is ​​calculated, eliminating the coupling interference between the sagittal and coronal plane motions. This allows the control quantities of the two degrees of freedom to be calculated and triggered independently, avoiding the control errors generated by the simple angle component projection method during large-angle motions, and improving the accuracy and stability of the two-degree-of-freedom control. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the overall structure of the active dual-degree-of-freedom ankle-foot exoskeleton device in the first preferred embodiment of the present invention. Figure 2 This is a schematic diagram of the circuit driving module of the active dual-degree-of-freedom ankle-foot exoskeleton device in the first preferred embodiment of the present invention; Figure 3 This is a flowchart of the control method for the active dual-degree-of-freedom ankle-foot exoskeleton device in the second preferred embodiment of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0044] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0045] It should be noted that when a component is referred to as "set on" another component, it can be directly on the other component or it can exist in the middle of the component.

[0046] When one element is considered to be "connected" to another element, it can be a direct connection or there may be an intervening element present.

[0047] The terms "sagittal plane," "coronal plane," "dorsiflexion," "plantar flexion," "inversion," and "eversion" used in this document are conventional anatomical terms in the field and are used for illustrative purposes only, and do not limit the only implementation of the present invention.

[0048] like Figure 1 As shown, the first preferred embodiment of the present invention discloses an active dual-degree-of-freedom ankle-foot exoskeleton device 100 based on collaborative control. The device 100 is mainly used to assist stroke patients in correcting abnormal gait patterns such as foot drop and circling gait.

[0049] The device 100 includes a leg fixation component 110, a foot fixation component 120, a foot-leg connection component 130, a drive component 140, a signal acquisition module 150, and a control module 160. All of the above components work together to achieve independent active control of the two degrees of freedom of the ankle joint in the sagittal and coronal planes.

[0050] Specifically, the aforementioned leg fixing component 110 includes a fixing rod 111 and a tensioning mechanism 112 disposed on one side of the fixing rod 111. The fixing rod 111 is fixed to the wearer's lower leg by the tensioning mechanism 112. More specifically, the fixing rod 111 extends longitudinally along the lower leg and is fixed to the wearer's lower leg by the tensioning mechanism 112. To improve the wearer's comfort, the outer contour of the fixing rod 111 fits the contour of the lower leg.

[0051] More preferably, the aforementioned fixing rod 111 is made of aluminum alloy, with an overall weight of no more than 350g, and its length can be extended and adjusted within a range of ±30mm to accommodate wearers of different heights.

[0052] The inner side of the fixing rod 111 is provided with a high-strength silicone pad, which is flexibly coupled to the wearer's calf through the tensioning mechanism 112. The tensioning mechanism 112 preferably adopts a Velcro adjustable strap structure to ensure the fixing strength while avoiding pressure on soft tissue.

[0053] On the other hand, in a more preferred embodiment of this invention, the tensioning mechanism 112 may include two sets of straps (not shown in the figure), which are located near the upper and lower ends of the fixing rod 111, respectively, and are used to fix the upper part of the lower leg and the ankle joint, so that the fixing rod 111 can maintain a stable relative position with the lower leg throughout the entire walking cycle and prevent the fixing rod 111 from sliding axially due to gait movements.

[0054] The aforementioned foot fixation assembly 120 includes a foot support 121 and a foot fixation member 122 fixed to one end of the foot support 121.

[0055] The foot support 121 is used to support the wearer's foot. Specifically, one end of the foot support 121 is located at the wearer's heel, and the other end extends forward along the midline of the wearer's foot to form a spatially stable support structure for the foot. In this embodiment, the shape of the foot support 121 is roughly matched with the shape of the wearer's foot. The size can be the same as or smaller than the wearer's foot, as long as it allows the wearer to stably place the foot support 121 under their foot and support the wearer's foot. Preferably, the foot support 121 is made of carbon fiber composite material, which has sufficient rigidity to transmit driving torque, and is also lightweight and comfortable.

[0056] The end of the foot support 121 near the wearer's heel is connected to the foot-leg connection assembly 130, and the leg fixing assembly 110 connected to the foot-leg connection assembly 130 limits the heel part of the foot support 121, making it difficult for the wearer's heel part to fall off the foot support 121.

[0057] The aforementioned foot fixing member 122 is located near the center of the wearer's sole of the foot support member 121, and is fixed to the wearer's instep by a strap.

[0058] In this way, the foot support 121 and the foot fixation 122 together form a three-point fixation structure through straps, ensuring that there is no relative slippage between the foot and the exoskeleton throughout the entire walking cycle.

[0059] The foot-leg connection assembly 130 has a connecting rod 131, a first hinge structure 132 and a second hinge structure 133. One end of the connecting rod 131 is connected to one end of the fixing rod 111 of the leg fixing assembly 110 through the first hinge structure 132, and the other end of the connecting rod 131 is connected to the end of the foot support 121 of the foot fixing assembly 120 near the wearer's heel through the second hinge structure 133.

[0060] In this embodiment, one end of the foot-leg connection component 130 connected to the fixing rod 111 can be close to the anterior position of the inner side of the wearer's ankle joint, while the other end of the foot-leg connection component 130 is connected to the end of the foot support component 121 close to the wearer's heel through the second hinge structure 133.

[0061] The end of the foot-leg connector 130 that is close to the heel can be located on the lateral and posterior side of the ankle joint, which facilitates the relative rotation of the leg fixation component 110 and the foot fixation component relative to the foot-leg connector 130.

[0062] The rotation axis of the first hinge structure 132 is parallel to the sagittal axis of the human body, corresponding to the dorsiflexion / plantar flexion movement of the ankle joint in the sagittal plane; the rotation axis of the second hinge structure 133 is parallel to the coronal axis of the human body, corresponding to the inversion / eversion movement of the ankle joint in the coronal plane.

[0063] The axes of the two hinge components are orthogonal to each other, forming a two-degree-of-freedom mechanical decoupling structure, which makes the sagittal plane control and the coronal plane control independent of each other at the mechanical level.

[0064] Combination Figure 1 and Figure 2As shown, the drive assembly 140 includes a first drive motor 141 and a second drive member 142. The first drive motor 141 and the second drive member 142 are two independent drive units. The first drive motor 141 is disposed on one side of the first hinge structure 132 and is controlled and driven by the control module 160 to rotate the first hinge structure 132, so that the fixed rod 111 rotates relative to the connecting rod 131 in the sagittal plane around the first hinge structure 132. The second drive member 142 is used to drive the second hinge structure 133, so that the connecting rod 131 rotates relative to the foot support member 121 in the coronal plane around the second hinge structure 133.

[0065] In this embodiment, the first drive motor 141 is installed on the inner side of the ankle joint of the wearer and is driven to connect with the first hinge structure 132, so that the fixing rod 111 of the leg fixing component 110 rotates relative to the connecting rod 131 of the foot and leg connecting component 130, thereby realizing the degree of freedom of dorsiflexion / plantar flexion movement of the ankle joint in the sagittal plane.

[0066] In this embodiment, the rated torque of the first drive motor 141 is not less than 0.5 N•m, and the peak torque is not less than 1.2 N•m.

[0067] The second driving member 142 is installed on the lateral side of the ankle joint and is driven to connect with the second hinge structure 133, so that the foot support member 121 of the foot fixation assembly 120 rotates relative to the connecting rod 131 of the foot and leg connection assembly 130, thereby realizing the degree of freedom of inversion / eversion movement of the coronal plane of the ankle joint.

[0068] Specifically, in the first embodiment of this implementation, the second driving member 142 is a second damping member. The second damping member can be manually adjusted and driven, thereby driving the second hinge structure 133, and thus causing the connecting rod 131 to rotate around the foot support 121 in the coronal plane.

[0069] In a more preferred second embodiment of this implementation, the second driving member 142 is a second driving motor, which is disposed on one side of the second hinge structure 133 to drive the second hinge structure 133 to rotate.

[0070] The second drive motor is controlled and driven by the control module 160.

[0071] To achieve the freedom of inward and outward tumbling, the second drive motor has a rated torque of not less than 0.3 N•m and a peak torque of not less than 0.8 N•m.

[0072] The aforementioned signal acquisition module 150 includes an inertial measurement unit 151 disposed on the instep and lower leg and a pressure sensor array 152 distributed on the sole of the foot. The inertial measurement unit 151 is used to acquire three-dimensional posture data of the foot and lower leg in real time, and the pressure sensor array 152 is used to acquire sole pressure information in real time.

[0073] In this embodiment, the inertial measurement unit 151 has an IMU sensor installed on the wearer's foot and lower leg. The IMU sensor includes a three-axis accelerometer and a three-axis gyroscope. The sampling frequency of the IMU sensor is not less than 200Hz, and it is used to acquire the attitude matrix of the foot relative to the world frame in real time.

[0074] The aforementioned pressure sensor array 152 is distributed on the sole of the wearer's foot, specifically in the area from the heel to the forefoot, with a sampling frequency of not less than 100Hz, and is used to detect the pressure distribution signal on the sole of the wearer's foot.

[0075] The control module 160 is electrically connected to the signal acquisition module 150 and is used to control the drive assembly 140 to work based on the three-dimensional posture data of the foot and lower leg and the plantar pressure information acquired by the signal acquisition module 150, so as to at least make the fixed rod 111 rotate relative to the foot and leg connection assembly around the first hinge structure 131.

[0076] Specifically, in the first preferred embodiment described above, the control module 160 only controls the first drive motor 141, and thus only controls the fixing rod 111 of the leg fixing component 110 to rotate relative to the connecting rod 131 of the foot and leg connecting component 130.

[0077] In the second preferred embodiment described above, the control module 160 controls the first drive motor 141 and the second drive motor, thereby controlling the rotation of the fixing rod 111 of the leg fixing assembly 110 relative to the connecting rod 131 of the foot-leg connecting assembly 130, and also controlling the rotation of the foot support member 121 of the foot fixing assembly 120 relative to the connecting rod 131 of the foot-leg connecting assembly 130.

[0078] Specifically, the control module 160 has a preset spatial geometric mapping model, which abstracts the longitudinal anatomical axis of the wearer's lower leg as the Z-axis, the axis from the wearer's heel to the toe as the X-axis, and establishes a transverse Y-axis perpendicular to the X-axis on the horizontal plane where the X-axis is located.

[0079] This spatial geometric mapping model can be used to store individualized reference parameters, which are determined by the initial anatomical angles of the Z-axis relative to the Z-axis and Y-axis measured by the signal acquisition module 150 when the wearer is in a free standing state.

[0080] The control module 160 controls the projection of the first drive motor in the sagittal plane to control the degrees of freedom of dorsiflexion and plantarflexion, based on the signals collected by the signal acquisition module 150, and controls the degrees of freedom of inversion and eversion through the projection of the second drive motor in the coronal plane.

[0081] The control module 160 achieves synchronous correction of foot drop and circumduction gait by controlling the first and second drive motors to work together on their respective projection surfaces.

[0082] The device 100 described in the above embodiment is driven independently by the first drive motor 141 and the second drive member 142 of the drive assembly 140, so that the fixed rod can rotate in the sagittal plane around the first hinge structure relative to the foot-leg connection assembly, and the foot-leg connection assembly can rotate in the coronal plane around the second hinge structure relative to the foot support member. Thus, active assistance of two degrees of freedom of ankle joint dorsiflexion / plantar flexion and inversion / eversion can be realized simultaneously on a single device, and active intervention can be provided for two types of movement disorders, namely foot drop and foot inversion / eversion.

[0083] To better illustrate the control process of the control module 160 controlling the drive component 140 in the first embodiment, the second preferred embodiment of the present invention also discloses a control method for the device 100. This control method can control the operation of the first drive motor 141 and the second drive member 142. In other words, the second drive member 142 is a second drive motor. Specifically, in conjunction with... Figure 3 As shown, the control method includes: S10: Acquire the three-dimensional posture data of the foot and lower leg and the plantar pressure information collected by the signal acquisition module; In this step, the signal acquisition module 150 acquires three-dimensional posture data of the lower leg and foot through the IMU sensor, and acquires the wearer's plantar pressure information through the pressure sensor. The IMU sensor is fixed in the area of ​​the wearer's instep, close to the surface of the foot, and moves synchronously with the foot. It acquires three-dimensional posture data such as three-axis acceleration and three-axis angular velocity of the foot relative to the world coordinate system in real time. The three-dimensional posture data is obtained by the posture conversion associated with the rigid rod bound to the lower leg. The synchronous acquisition of the lower leg spatial posture is achieved by the rigid coupling between the fixed rod and the lower leg.

[0084] The aforementioned pressure sensor array is distributed in two key pressure-bearing areas: the heel area and the forefoot metatarsal area.

[0085] Specifically, the aforementioned pressure sensor array in the heel area is located near the wearer's heel on the aforementioned support member, collecting the sudden pressure change signal at the moment the heel touches the ground.

[0086] Pressure sensors distributed in the metatarsal region of the forefoot collect data on the pressure on the forefoot when the toes leave the ground. The presence or absence of pressure is used to determine changes in pressure amplitude and distinguish between the foot landing or airborne states.

[0087] In this embodiment, the foot and lower leg IMUs continuously and synchronously output 6 channels of raw physical signals: instantaneous acceleration and instantaneous angular velocity in the X / Y / Z axes, with a high frequency sampling of 200Hz. The foot pressure sensor has a sampling frequency of 100Hz, continuously recording the spatial dynamic motion data of the foot in the world inertial coordinate system.

[0088] The signal acquisition module uses clock stamping and interpolation to align the timing of attitude data and pressure data, ensuring that the attitude and plantar pressure at the same moment correspond one-to-one.

[0089] Low-pass filtering is used to remove high-frequency noise from sensors caused by walking vibration and exoskeleton mechanical shaking, and abnormal jump data is removed before sampling data is preprocessed.

[0090] After preprocessing, the data is temporarily cached locally in the acquisition module and then packaged and uploaded to the control module in batches according to a fixed control cycle (50ms).

[0091] S20: Form the foot rotation matrix within the constructed spatial geometric mapping model. and lower leg rotation matrix The relative foot-leg rotation matrix is ​​obtained. .

[0092] In this embodiment, the above-mentioned spatial geometric mapping model abstracts the longitudinal anatomical axis of the lower leg as the Z-axis, the direction from the heel to the toe as the X-axis, and establishes a horizontal line Y-axis perpendicular to the X-axis on the horizontal plane, thus forming a three-dimensional spatial geometric model of the right-hand coordinate system {X, Y, Z}.

[0093] In this embodiment, static data acquisition of the wearer while standing freely can be obtained first. Specifically, the wearer stands naturally upright with both feet firmly on the ground (without weight-bearing or limb swinging). The acquisition module starts static calibration: continuously acquires static posture data of the lower leg Z-axis relative to the X and Y axes for 3-5 seconds, calculates the initial anatomical angles of Z-X and Z-Y, and stores them in the control unit as individualized reference parameters to correct the zero-point deviation of subsequent dynamic walking posture acquisition (eliminating acquisition system errors caused by individual leg shape and ankle physiological deviation angles).

[0094] In the three-dimensional spatial geometric model, based on the gyroscope integration and accelerometer gravity correction of the aforementioned signal acquisition module, the rotation matrix of the foot relative to the world coordinate system is calculated in real time. By combining the mechanical assembly geometric constraints of the lower leg fixation rod with the individualized baseline anatomical angle parameters of the wearer's standing calibration, the rotation matrix of the lower leg relative to the world coordinate system is calculated. .

[0095] The relative foot-leg rotation matrix with respect to the lower leg satisfy:

[0096] in, For the rotation matrix of the lower leg The transpose of .

[0097] S30: Based on the relative rotation matrix of the foot and leg The decoupling process obtains the first free angle of the fixed rod relative to the foot-leg connection assembly in the sagittal plane around the first hinge structure, and the second free angle of the foot-leg connection assembly relative to the foot support member around the second hinge structure. When the first free angle exceeds the corresponding angle threshold, the first drive motor is triggered to control the first free angle. When the second free angle exceeds the angle threshold, the second drive motor is triggered to control the second free angle.

[0098] The above foot-leg relative rotation matrix The foot-leg relative rotation matrix output by S20 above. In this embodiment, the above-mentioned rotation matrix It can be a 3×3 orthogonal rotation matrix, which fully represents the spatial rotation relationship between the foot coordinate system and the lower leg reference coordinate system. (m, n) represents the element in the m-th row and n-th column of the matrix, which is the unique original parameter for angle calculation.

[0099] The aforementioned first free angle The rotation angle of the first hinge structure is the rotation angle of the fixed rod relative to the leg connection assembly in the sagittal plane, which enables the ankle joint to move in the sagittal plane and the foot to swing up and down.

[0100] Generally, when When >0, the ankle joint is in a dorsiflexed position. <0 indicates that the ankle joint is in plantar flexion, at which point the wearer's toes are drooping, a typical pathological posture for stroke.

[0101] Specifically, the aforementioned first free angle satisfies:

[0102] In the above formula, This is a four-quadrant arctangent function, distinct from the ordinary arctangent, capable of outputting a complete range of radians (-π, π), distinguishing the pitch direction in all four quadrants, and accurately identifying two foot movements: upward dorsiflexion and downward plantarflexion. In this formula, the element in the second row and first column of the relative rotation matrix is ​​used. Element in row 1 and column 1 After symbolic correction, the result is inserted into the above function.

[0103] Second Free Angle The angle of rotation of the foot-leg connection component relative to the foot support component in the coronal plane around the second hinge structure: a positive value represents ankle eversion, in other words, the wearer's foot is in an outward-opening state; a negative value represents ankle inversion, in other words, the wearer's foot is in an inward-curving state. This is the second free angle. satisfy:

[0104] In the above formula, Arcsine function, output range [- It is designed to fit the physiological eversion / inversion range of motion of the ankle joint.

[0105] In this step, the trigonometric function components corresponding to the row and column elements of the rotation matrix are used to decompose the composite three-dimensional rotation of the foot relative to the lower leg into two independent joint angles: sagittal flexion-extension and coronal roll, thus completing the mapping of spatial posture to mechanical joint angles.

[0106] S40: Import the acquired three-dimensional posture data of the foot and lower leg, as well as the plantar pressure information, into the constructed gait recognition model to obtain the wearer's current gait information.

[0107] This step acquires the three-dimensional posture data of the lower leg and foot, as well as plantar pressure information. Using either a Hidden Markov Model (HMM) or a Finite State Machine (FSM) algorithm, four mutually exclusive gait phases are identified in real time: heel strike, full foot support, toe lift, and swing phase. The identification results serve as the basis for phase switching in downstream motor triggering, circling gait eversion control, and variable stiffness impedance control, thereby achieving phased differentiated rehabilitation and correction control.

[0108] The four phases mentioned above are mutually exclusive, and only one state is output at any given time: the heel-to-ground phase is when the heel touches the ground first, the forefoot is suspended in the air, and it is the initial stage of the gait cycle; the full foot support phase is when the heel and forefoot are fully on the ground, the affected limb bears the body weight, and it is the stable standing phase; the toe-off phase is when the heel leaves the ground, only the forefoot pushes off, the body's center of gravity shifts forward, and it is the transition phase of stepping off the ground; the swing phase is when the entire foot is completely off the ground and suspended in the air, the lower limb swings forward to take a step, and it is the main correction range for foot drop, foot inversion, and circling gait.

[0109] Specifically, the judgment process of the aforementioned finite state machine (FSM) algorithm is as follows: S1: The pressure at the heel measuring point on the sole of the foot suddenly increases from 0 to above the preset pressure threshold, while the forefoot pressure remains low; the angular velocity of the lower leg / foot experiences a sudden change in impact upon landing, indicating the onset of the heel contact phase; S2: While the heel pressure stabilizes, the pressure in the metatarsal region of the forefoot simultaneously exceeds the landing threshold, and the entire foot contacts the ground, switching to full-foot support; S3: The heel pressure drops below the threshold, and only the forefoot toe area retains effective pressure, while the ankle sagittal angle... Start lifting upwards (dorsiflexion), switch to the toe-off phase; S4: All pressure measurement points on the entire sole are below the landing threshold (foot is completely off the ground and suspended), the foot's Z-axis acceleration increases, the toe-off height htoe continues to increase, and enter the swing phase; the swing phase ends, the heel lands again and returns to the above S1, completing the single-step closed-loop cycle.

[0110] The aforementioned finite state machine (FSM) has simple logic, low computational cost, and is easy to implement with embedded main control.

[0111] Hidden Markov Models (HMMs) are trained using a large number of gait samples from healthy / stroke patients to obtain state transition probability matrices and observation probability matrices. Then, the signals collected by the signal acquisition module are acquired and combined to form multidimensional observation features, which include heel pressure, forefoot pressure, lower leg angular velocity, sagittal angle, and coronal angle.

[0112] The model receives real-time observation vectors, uses the Viterbi algorithm to solve for the hidden gait state with the highest probability at the current moment, and outputs the current phase.

[0113] The aforementioned Hidden Markov Model (HMM) has stronger resistance to sensor noise, high recognition accuracy when facing spastic gait and irregular pathological walking, and is suitable for various scenarios with deformed gait.

[0114] S50: Based on the high intervention model, determine whether the first free angle of the wearer in the current gait information exceeds the first safety threshold. If it does, compensate the control amount of the first drive motor driving the first hinge structure.

[0115] Specifically, the height-based intervention model includes a height detection unit, a height prediction unit, and a height compensation unit, wherein the height detection unit satisfies:

[0116] in, For toe height detection, The velocity of the wearer's lower leg in the vertical direction. The distance from the center of the wearer's ankle joint to the toes. The angle of the wearer's lower leg relative to the vertical line. The dorsiflexion / plantarflexion angle, For foot structural parameters, For the current moment, The starting time; The height prediction unit satisfies:

[0117] in, Predicting height for the toes For toe height detection, The rate of change of toe height at the current moment. Let be the second derivative of the current toe height; The height compensation unit satisfies:

[0118] in, The minimum height threshold, To compensate for the gain, To compensate for the torque exerted by the first drive motor on the first hinge structure.

[0119] In this step, the above-mentioned technical solution relies on second-order Taylor prediction to achieve feedforward compensation, which is different from passive correction after landing. It prevents toe dragging on the ground in advance and greatly optimizes the problem of foot drop in the swing phase of stroke. It uses integral terms and geometric cosine compensation of the human foot to correct the toe height error caused by lower leg swing and ankle flexion and extension, which is more accurate than simple IMU integral height measurement. The closer to the safety lower limit of the ground, the linear increase of the compensation torque, which takes into account both compliance and corrective force, and will not restrict the patient's autonomous movement due to excessive motor rigidity.

[0120] S60: Based on the circling compensation model, determine whether the wearer's movement trajectory in the current gait information exceeds the error threshold. If it does, compensate the control amount of the second drive motor driving the second hinge structure.

[0121] The above-mentioned circle-based compensation model satisfies:

[0122] in, For composite compensation torque, The first adjustment coefficient, This is the second adjustment coefficient. For gravity compensation, For the error in the foot's trajectory in the coronal plane, , Fittings can be clinically determined based on the severity of the patient's inversion, making them suitable for patients with varying degrees of hemiplegia. The foot's trajectory error in the coronal plane satisfy:

[0123] The For the coronal reference trajectory, For the actual trajectory in the coronal plane, gravity compensation term satisfy:

[0124] The The total mass of the foot. It is the acceleration due to gravity. This is the distance from the foot's center of mass to the ankle joint's axis of rotation. The angle of inclination of the foot relative to the direction of gravity.

[0125] The above steps use dynamic PD to eliminate trajectory deviation and static feedforward to offset the self-weight inversion torque. Compared with single PD control, it significantly reduces steady-state error and provides smoother correction. Only the swing phase is compensated, and no eversion torque is applied during the landing support phase, ensuring standing stability and improving wearing comfort. It also inhibits foot inversion from the coronal plane, avoiding foot inversion that causes the hip joint to be forced to abduct and draw a semi-circle, thus improving the circumduction compensatory gait of stroke from the pathological root.

[0126] Based on the collaborative control model, the wearer's foot inversion or eversion angle in the coronal plane is controlled according to the current toe detection height. The collaborative control model satisfies:

[0127] in, The target control angle for the coronal plane. The neutral posture angle of the foot (the baseline eversion / inversion angle during normal walking). For the cooperative control gain coefficient, Toe height is measured.

[0128] The aforementioned collaborative control module enables cross-degree-of-freedom collaborative linkage, using sagittal plane toe height to link coronal eversion, conforming to the physiological logic of human walking. The toes must land simultaneously with the foot spreading out, fundamentally avoiding toe inward dragging and hip joint compensatory circular motions. Relying on the nonlinear characteristics of the natural index, the eversion amount increases sharply when the toes are close to the ground and is almost zero when the toes are sufficiently off the ground, balancing normal compliance with strong correction in dangerous situations. The eversion sensitivity can be adjusted as a whole through a single coefficient, making clinical adjustment simple and suitable for hemiplegic patients with mild, moderate, and severe foot inversion. Moreover, the above model only works during the swing phase, maintaining neutrality during the landing phase, and there is no excess eversion torque when standing, ensuring the stability of the affected limb when standing.

[0129] The method further includes: Impedance control of joint motion is performed based on a damping control model, which satisfies the following:

[0130] in, This is the equivalent inertia of the joint. Joint angular acceleration, The damping coefficient is... The joint angular velocity, This is the stiffness coefficient. This refers to the actual angle of the joint. From the perspective of the target, For external torque, This refers to the motor torque.

[0131] The above-mentioned damping control model is a universal bottom-level impedance closed-loop control for ankle joint dual degrees of freedom. It is the torque execution layer for the above steps S50 sagittal motor compensation, S60 coronal circumduction compensation, and toe height coordinated eversion control. The impedance control model is built based on the classic second-order spring-damping dynamics equation.

[0132] The aforementioned damping control model utilizes the hardening of the pathological oscillation phase for forced correction and the softening of the normal gait for follow-up, achieving both deformity correction and preserving the patient's ability to exercise independently; it automatically deducts the patient's voluntary force, avoiding the problems of resistance between the motor and the human body and the suffocation caused by wearing the device; the sagittal and coronal dual motors share the same impedance model, allowing for the reuse of hardware and software architecture and simplifying the deployment of the controller algorithm.

[0133] The method described above in this invention constructs a spatial geometric mapping model to form foot rotation matrices. and calf rotation matrix Then, the relative foot and leg rotation matrix is ​​calculated, eliminating the coupling interference between the sagittal and coronal plane motions. This allows the control quantities of the two degrees of freedom to be calculated and triggered independently, avoiding the control errors generated by the simple angle component projection method during large-angle motions, and improving the accuracy and stability of the two-degree-of-freedom control.

[0134] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The above embodiments are merely examples of several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent.

[0136] It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this invention, and these modifications and improvements are all within the scope of protection of this invention.

[0137] Therefore, the scope of protection of this invention patent shall be determined by the appended claims.

Claims

1. An active dual-degree-of-freedom ankle-foot exoskeleton device based on collaborative control, characterized in that, include: A leg fixation assembly includes a fixing rod and a tensioning mechanism disposed on one side of the fixing rod, wherein the fixing rod is fixed to the wearer's lower leg by the tensioning mechanism; A foot fixation component includes a foot support and a foot fixation component fixed to one end of the foot support. The foot support is used to support the wearer's foot, and the foot fixation component is located near the center of the wearer's sole and is fixed to the wearer's foot by a strap. The foot and leg connection assembly has a connecting rod and a first hinge structure and a second hinge structure located at both ends of the connecting rod. One end of the connecting rod is connected to one end of the fixed rod through the first hinge structure, and the other end is connected to the end of the foot support near the wearer's heel through the second hinge structure. The drive assembly includes a first drive motor and a second drive member. The first drive motor is used to drive the first hinge structure to rotate the fixed rod relative to the connecting rod in the sagittal plane around the first hinge structure. The second drive member is used to drive the second hinge structure to rotate the connecting rod relative to the foot support member in the coronal plane around the second hinge structure. The signal acquisition module includes an inertial measurement unit disposed on the instep and lower leg and a pressure sensor array distributed on the sole of the foot. The inertial measurement unit is used to acquire three-dimensional posture data of the foot and lower leg in real time, and the pressure sensor array is used to acquire sole pressure information in real time. The control module is electrically connected to the signal acquisition module and is used to control the operation of the drive component based on the three-dimensional posture data of the foot and lower leg and the plantar pressure information acquired by the signal acquisition module, at least to make the fixed rod rotate around the first hinge structure relative to the foot and leg connection component.

2. The active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 1, characterized in that, The second driving component is a second drive motor controlled by the control module. The second drive motor drives the foot-leg connection assembly to rotate relative to the foot support component around the second hinge structure.

3. The active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 2, characterized in that, The control module obtains the first rotation angle of the fixed rod relative to the foot and leg connecting component around the first hinge structure and the second rotation angle of the foot and leg connecting component relative to the foot support component around the second hinge structure based on the gait phase recognition algorithm, according to the three-dimensional posture data of the foot and lower leg and the plantar pressure information collected by the signal acquisition module. The control module then controls the first drive motor and the second drive motor to drive according to the corresponding rotation angle.

4. The active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 2, characterized in that, The second drive motor is located on one side of the second hinge structure and is used to drive the second hinge structure to rotate.

5. The active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 1, characterized in that, The first drive motor is located on one side of the first hinge structure and is used to drive the first hinge structure to rotate.

6. The active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 1, characterized in that, The inertial measurement unit includes a three-axis accelerometer and a three-axis gyroscope.

7. The active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 1, characterized in that, The second driving component is a second damping component, which controls the rotation of the foot-leg connection assembly relative to the foot support component around the second hinge structure component by manual adjustment.

8. A control method for an active dual-degree-of-freedom ankle-foot exoskeleton device based on cooperative control, used to control the active dual-degree-of-freedom ankle-foot exoskeleton device according to any one of claims 2 to 6, characterized in that, The method includes: The signal acquisition module acquires three-dimensional posture data of the foot and lower leg, as well as plantar pressure information. A foot rotation matrix is ​​formed within the constructed spatial geometric mapping model. and lower leg rotation matrix The relative foot-leg rotation matrix is ​​obtained. ; Based on the relative rotation matrix of the foot and leg The decoupling process obtains the first free angle of the fixed rod relative to the foot and leg connecting assembly in the sagittal plane around the first hinge structure, and the second free angle of the foot and leg connecting assembly relative to the foot support member around the second hinge structure. When the first free angle exceeds the corresponding angle threshold, the first drive motor is triggered to control the first free angle. When the second free angle exceeds the angle threshold, the second drive motor is triggered to control the second free angle. The acquired three-dimensional posture data of the foot and lower leg, as well as the plantar pressure information, are imported into the constructed gait recognition model to obtain the wearer's current gait information; Based on the high intervention model, it is determined whether the first free angle of the wearer in the current gait information exceeds the first safety threshold. If it does, the control amount of the first drive motor driving the first hinge structure is compensated. Based on the circling compensation model, it is determined whether the wearer's movement trajectory in the current gait information exceeds the error threshold. If it does, the control amount of the second drive motor driving the second hinge structure is compensated.

9. The control method for the active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 8, characterized in that, The relative foot-leg rotation matrix with respect to the lower leg satisfy: ； in, For the rotation matrix of the lower leg The transpose of .

10. The control method for the active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 8, characterized in that, The first free angle satisfies: ； The second free angle satisfies: ； in, As the first free angle, This is the second free angle.

11. The control method for the active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 10, characterized in that, The process involves importing the acquired three-dimensional posture data of the foot and lower leg, along with plantar pressure information, into the constructed gait recognition model to obtain the wearer's current gait information, including: The gait recognition model uses a gait phase recognition algorithm based on a hidden Markov model or a finite state machine. Based on the acquired three-dimensional posture data of the foot and lower leg and plantar pressure information, it obtains four mutually exclusive gait information of the wearer. The gait information includes heel strike, full foot support, toe lift, and swing phase.

12. The control method for the active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 10, characterized in that, The height-based intervention model includes a height detection unit, a height prediction unit, and a height compensation unit, wherein the height detection unit satisfies: ； in, For toe height detection, The velocity of the wearer's lower leg in the vertical direction. The distance from the center of the wearer's ankle joint to the toes. The angle of the wearer's lower leg relative to the vertical line. The dorsiflexion / plantarflexion angle, For foot structural parameters, For the current moment, The starting time; The height prediction unit satisfies: ； in, Predicting height for the toes For toe height detection, The rate of change of toe height at the current moment. Let be the second derivative of the current toe height; The height compensation unit satisfies: ； in, The minimum height threshold, To compensate for the gain, To compensate for the torque exerted by the first drive motor on the first hinge structure.

13. The control method for the active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 12, characterized in that, The method further includes: Based on the collaborative control model, the wearer's foot inversion or eversion angle in the coronal plane is controlled according to the current toe detection height. The collaborative control model satisfies: ； in, The target control angle for the coronal plane. The neutral posture angle of the foot (the baseline eversion / inversion angle during normal walking). For the cooperative control gain coefficient, Toe height is measured.

14. The control method for the active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 10, characterized in that, The circle-based compensation model satisfies: ） ； in, For composite compensation torque, The first adjustment coefficient, This is the second adjustment coefficient. For gravity compensation, The foot trajectory error in the coronal plane. satisfy: ； The For the coronal reference trajectory, For the actual trajectory in the coronal plane, gravity compensation term satisfy: ； The The total mass of the foot, It is the acceleration due to gravity. This is the distance from the foot's center of mass to the ankle joint's axis of rotation. The angle of inclination of the foot relative to the direction of gravity.

15. The control method for the active dual-degree-of-freedom ankle-foot exoskeleton device according to claim 8, characterized in that, The method further includes: Impedance control of joint motion is performed based on a damping control model, which satisfies the following: ； in, This is the equivalent inertia of the joint. Joint angular acceleration, The damping coefficient is... The joint angular velocity, This is the stiffness coefficient. This refers to the actual angle of the joint. From the perspective of the target, For external torque, This refers to the motor torque.

Images