Total knee replacement postoperative patient walking assisting method with hexapod robot as prototype

Abstract

The invention relates to the technical field of postoperative patient walking assisting, and discloses a total knee replacement postoperative patient walking assisting method with a hexapod robot as a prototype, and the method comprises the steps: collecting the height and hip joint height of a patient; based on the height of the patient and the hip joint height, the walking height of the walking aid is dynamically adjusted by controlling the prediction model; the front terrain environment is recognized through the sensor assembly, so that the walking aid executes the procedures of advancing on the flat ground, climbing steps and going down stairs. The problems that a traditional walking aid is poor in universality and limits the movement range of a patient are solved, and the movement stability of the patient, the comfort of a user and the mechanical safety are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of walking assistance for patients after surgery, and in particular to a walking assistance method for patients after total knee replacement surgery using a hexapod robot as a prototype. Background Art

[0002] With the advancement of technology, traditional wheelchairs and walkers are no longer able to meet the daily rehabilitation needs of patients after total knee replacement surgery. Traditional wheelchairs are convenient for use on flat ground, but they are inadequate for patients undergoing total knee replacement surgery to meet their rehabilitation needs, go up and down stairs, and navigate more complex roads.

[0003] A walker is a device used to assist patients in walking after surgery, particularly those recovering from lower limb surgery. It supports their weight, allowing them to walk or perform rehabilitation. Existing walkers typically consist of a main frame and a rolling element. The rolling element, located at the bottom of the main frame, provides support for the patient's hands, while the rolling element facilitates movement on flat ground.

[0004] However, various areas and roads often have steps and ditches that require people to walk over. However, because patients who have undergone lower limb surgery and use walkers always need the support of the walker, they cannot lift the walker to walk over them. This makes it impossible for patients to cross steps and ditches, which seriously limits their range of movement. Therefore, existing walkers are not universal and cannot help patients complete a full range of walking. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of poor versatility of traditional walkers and limited range of motion of patients, and to improve patient movement stability, user comfort and mechanical safety, and to provide a walking assistance method for patients after total knee replacement surgery based on a hexapod robot.

[0006] In order to achieve the above-mentioned object of the invention, the embodiment of the present invention provides the following technical solutions:

[0007] A method for assisting patients with total knee replacement surgery using a hexapod robot as a prototype includes the following steps:

[0008] Step 1: Collect the patient's height and hip height;

[0009] Step 2: Based on the patient's height and hip joint height, the walker handrail height is dynamically adjusted through the control prediction model;

[0010] Step 3: Identify the terrain environment ahead through the sensor assembly, and enable the walker to execute the procedures of walking on flat ground, climbing steps, and going down stairs.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The present invention proposes a walker for use in multiple scenarios to solve the current difficulties encountered by patients, which is becoming increasingly urgent. This walker can effectively improve the quality of life of patients, enable them to complete rehabilitation training personally, and be able to participate in social activities more freely. The device adopts a hexapod design and each leg has multiple degrees of freedom and is equipped with wheels. This hybrid configuration allows the robot to flexibly switch its movement mode on different terrains such as flat ground and stairs. On flat ground, the robot can use wheels to move quickly; in places with height differences such as stairs, it can use a combination of wheels and legs to move up and down. This design ensures that there are multiple contact points with the ground at all times, providing full-time stability and efficient movement performance. Cooperating with the control prediction model (MPC) algorithm for dynamically adjusting the height of the walker handrail, it takes into account the patient's movement stability, user comfort and mechanical safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 Flow chart of the method of the present invention;

[0015] Figure 2 This is a schematic structural diagram of a hexapod robot according to an embodiment of the present invention;

[0016] Figure 3 This is a structural block diagram of a control system according to an embodiment of the present invention;

[0017] Figure 4 This is a structural block diagram of a control prediction model according to an embodiment of the present invention;

[0018] Figure 5 This is a simplified structural diagram of the hexapod robot of the present invention when it is standing;

[0019] Figure 6 Schematic diagram of the height of the mechanical feet of the hexapod robot of the present invention when climbing stairs.

[0020] Description of main component symbols

[0021] Main support 1; handrail 2; mechanical foot 3. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0023] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures. At the same time, in the description of the present invention, the terms "first", "second", etc. are used only to distinguish the description and are not to be understood as indicating or implying relative importance, or implying any actual relationship or order between these entities or operations. In addition, the terms "connected" and "connected" can refer to direct connection between elements or indirect connection via other elements.

[0024] Example 1:

[0025] The present invention is achieved through the following technical solutions: Figure 1 As shown, a method for assisting patients with total knee replacement surgery using a hexapod robot as a prototype includes the following steps:

[0026] Step 1: Collect the patient's height and hip height.

[0027] A patient database is established to record basic patient information, including name, gender, age, height, and weight. This database facilitates follow-up rehabilitation. Recording the recovery progress of total knee replacement patients using walkers is a key function of the database, facilitating subsequent rehabilitation assessments.

[0028] like Figure 2 As shown, the walker achieves multi-terrain adaptation through a hexapod mechanical system. The patient enters the walker's central ring-shaped main support 1 and holds onto handrails 2 for support. Given the diverse body shapes and postures of patients undergoing total knee replacement surgery, the walker's handrail height (i.e., main support height) varies based on the patient's height and hip joint height. This allows the motor to control the walker's hexapod mechanical system to move forward, backward, and rotate left and right, completing the walking process.

[0029] The walker is based on the mechanical structure of a mobile wheeled hexapod robot. Each mechanical foot is equipped with a roller. In order to meet the control requirements of the system, the mechanical feet of the mobile wheeled hexapod robot are controlled in motion. Figure 3 As shown, the control system includes a power module, processor, sensor assembly, drive circuit, actuator, and human-machine interface. The sensor assembly includes infrared and ultrasonic sensors. The infrared sensor detects the patient's stride length, cadence, and speed, assisting in the synchronous control of the six legs. The ultrasonic sensor collects information about the terrain and environment for obstacle avoidance. Based on the patient's walking pattern and the terrain, the processor amplifies the control signal, and the drive circuit then uses motors to control the mechanical legs to move forward, backward, and rotate left and right. The human-machine interface can handle emergency braking, wheel-leg switching for ascending and descending stairs, and walking on flat ground. It prioritizes user experience and can be customized to suit different user needs. The power module provides power to all components.

[0030] Step 2: Based on the patient's height and hip joint height, the walker handrail height is dynamically adjusted through the control prediction model.

[0031] The control prediction model (MPC) algorithm for dynamically adjusting the height of the walker handrail is introduced and runs in the processor to take into account the patient's movement stability, user comfort and mechanical safety. Figure 4 As shown in Figure 3, the structure of the control prediction model (MPC) includes a reference trajectory, a state observer, a rolling optimizer, an actuator, a hexapod mechanical system, and a terrain environment, and forms a closed-loop feedback.

[0032] Reference trajectory x t (k) is dynamically generated by the patient's height, hip joint height, and the terrain environment collected by the ultrasound sensor, and the desired height is output to the state observer, which estimates the current state x(k) in real time. The state observer uses a linear discrete state space model to describe the dynamic adjustment process of the handrail height. Its dynamic equation is:

[0033] x(k+1)=Ax(k)+Bu(k)

[0034] y(k)=Cx(k)

[0035] where k is the discrete time index; x(k) = [h(k), Δh(k)] T is the state variable at time k, h(k) represents the current handrail height, Δh(k) represents the height change rate, and T represents the matrix transpose; x(k+1) is the state variable at time k+1; u(k) is the control input, that is, the adjustment amount of the drive motor; y(k) is the system output, that is, the actual handrail height (main support height); matrices A, B, and C represent the state transfer matrix, control input matrix, and output matrix, respectively, which are determined through system identification.

[0036] The rolling optimizer calculates the optimal value at each sampling time k based on the current state x(k) and the reference trajectory x t (k), rolling optimization of the control sequence {u(k|k),u(k+1|k),...,u(k+P-1)|k} for the next P steps to minimize the performance index J:

[0037]

[0038] Among them, Q is the state error weight matrix, which is used to adjust the height tracking accuracy; R is the control input weight matrix, which is used to limit the motor adjustment range and reduce energy consumption; x(k+i|k) represents the state variable predicted in the future i-th step at the current time k; x i (k+i|k) represents the reference trajectory predicted for the future i-th step at the current time k; u(k+i|k) represents the control input for the future i-th step to be optimized; i = 0, 1, 2, ..., P-1.

[0039] To ensure safety and comfort, the rolling optimization process must satisfy the following mechanical limit constraints:

[0040] h min ≤h(k+i|k)≤h max

[0041] Among them, h(k+i|k) represents the predicted handrail height of the i-th step in the future at the current time k; h min is the minimum allowed height; h max is the maximum allowed height.

[0042] The rate constraint is as follows:

[0043] |Δh(k+i|k)≤Δh max |

[0044] Where Δh(k+i|k) represents the handrail height adjustment rate; Δh max Indicates the maximum allowed adjustment rate.

[0045] The comfort threshold is as follows:

[0046] |Δh(k+i|k)≤δ comfort |

[0047] Among them, δ comfort Indicates the maximum instantaneous altitude change that the user can accept.

[0048] The actuator, using an STM32 microcontroller and MOSFET driver circuits, converts the initial control input u(k|k) into a motor signal, which is then fed into the hexapod's mechanical system to adjust its altitude. When the terrain changes, the ultrasonic sensor triggers an update of the reference trajectory. The Predictive Control Model (MPC) uses rolling optimization to smoothly adjust the altitude, while simultaneously coordinating the hexapod's wheeled locomotion and foot-based climbing movements to ensure motion stability.

[0049] Step 3: Identify the terrain environment ahead through the sensor assembly, and enable the walker to execute the procedures of walking on flat ground, climbing steps, and going down stairs.

[0050] like Figure 5 The figure shows a simplified diagram of the hexapod robot's standing structure. The left front leg is designated L1, the middle leg L3, and the hind leg L5; the right front leg is designated R2, the middle leg R4, and the hind leg R6. The walker automatically switches between walking modes, using rollers to propel the robot forward on flat ground. Upon encountering a step, the rollers lock, with the hind legs supporting the ground while the front legs grip the step, and the middle leg synchronizes with the patient's legs. The rollers then unlock again when the ground is level.

[0051] The height from the highest point of each side of the mechanical foot to the ground is: front leg height h F , mid-leg height h M , hind leg height h H The vertical height output force f of the mechanical foot sty The two sides jointly determine the spatial posture of the main support plane, including its vertical height h, pitch angle α around the y-axis, and roll angle β around the x-axis. Motors control the rollers to achieve forward, reverse, and rotational movement. Infrared sensors monitor stride length, enabling the walker to gradually and smoothly decelerate to ensure patient safety and comfort, and confirming a stable gait before coming to a complete stop. Throughout this process, six mechanical legs maintain balance, and the motors adjust speed and direction based on signals from the sensor components, adaptively matching the patient's walking pattern.

[0052]

[0053] Among them, h L Indicates the average height of the left mechanical foot; h R represents the average height of the right mechanical foot; l represents the distance between adjacent mechanical feet on the same side; ω represents the annular diameter of the main stent.

[0054] Since the height of the mechanical foot is only affected by the vertical force, the spatial posture of the main support plane is determined by the vertical output force f of each mechanical foot. sty Control. sty Altitude tracking is achieved through proportional-differential control law, as shown below:

[0055]

[0056] Among them, hstd Indicates the desired height; h st Indicates the actual height of the current mechanical leg; k p Represents the proportional coefficient, which determines the response strength of the height deviation; k d Represents the differential coefficient, which suppresses the oscillation during the height adjustment process.

[0057] like Figure 6 As shown in the figure, when the ultrasonic sensor detects a step ahead, the system starts a three-stage climbing procedure. In the first stage, the hexapod robot first raises its left front leg L1 and right front leg R2 synchronously to a height h l , and h l Greater than the obstacle height h o , h l -h o =h s , h s To preset a safe distance, ensure that the robotic foot does not collide with obstacles. During the leg lifting process, the vertical force of the swinging robotic foot is f swy , and the swinging mechanical feet have no mutual force:

[0058] h l =h o +h s

[0059]

[0060] Among them, h swd Indicates the desired height of the swinging mechanical foot; h sw Indicates the actual height of the swinging mechanical foot; k p represents the proportional coefficient; k d represents the differential coefficient; Indicates h swd The rate of change of altitude; Indicates h sw After the left front leg L1 and the right front leg R1 are lifted, they swing forward to the upper step plane to provide stable support.

[0061] In the second stage, the left middle leg L3 and the right middle leg R4 are randomly driven to rise along the same trajectory. The movement process is monitored by the patient's lower limb swing amplitude θ h Perform adaptive adjustment:

[0062] Δv=K·|θ h -θ m |

[0063] Among them, Δv represents the change in swing amplitude; θ h Indicates the swing amplitude of the patient's lower limbs; θ m Indicates the preset standard swing; K indicates the adjustment gain coefficient.

[0064] In the third stage, finally control the left hind leg L5 and the right hind leg R6 to complete the step. Repeat the three stages until you have completed the stairs.

[0065] When the ultrasonic sensor detects flat ground ahead, the system initiates a three-stage flat-ground transition procedure. In the first stage, the front legs (L1 and R2) on both sides first contact the ground, providing a stable support point and ensuring that the robot has a solid foundation before commencing the flat-ground transition. In the second stage, the rollers of the middle legs (L3 and R4) on both sides are driven to unlock. The movement process is adaptively adjusted based on the swing amplitude of the patient's lower limbs monitored by infrared sensors. In the third stage, the two hind legs (L5 and R6) are gradually retracted to prepare for the roller unlocking. The rollers begin to rotate, ensuring that they are in full contact with the ground.

[0066] When the ultrasonic sensor detects that there are steps ahead, the system starts a three-stage stair descent procedure. In the first stage, the front legs (L1 and R2) on both sides are controlled to first contact the next step to provide stable support. In the second stage, the middle legs (L3 and R4) on both sides are driven to extend to the next step to ensure that the gripping point is stable. The infrared sensor monitors the swing amplitude of the patient's lower limbs and makes adaptive adjustments to keep it synchronized with the patient's movements. In the third stage, the hind legs (L5 and R6) on both sides are controlled to retract the support to complete the descent. In the process of going down the stairs, to ensure safety, the vertical force of the swinging mechanical foot is f swy , and each swinging mechanical foot is independent of each other and has no force influence, ensuring that each step is executed accurately.

[0067] f swy =m·g+F safety

[0068] Where m is the mass of the mechanical foot; g is the acceleration due to gravity; F safety It is an additional safety force used to compensate for possible instability and ensure the stability of each step.

[0069] Step 4: Extract the patient's lower limb swing data after using the walker, compare the swing data before and after using the walker, and complete the rehabilitation assessment.

[0070] The sensor component's output signal is amplified, filtered, and converted to digital to ensure data quality. The processed swing amplitude data is stored in the walker database, recording each use. Changes in swing amplitude before and after the patient uses the walker are compared and analyzed to assess rehabilitation progress. A detailed report with trend charts and scores is generated for the medical team and patient. Subjective feedback from patients is also collected and combined with objective data to comprehensively evaluate the effectiveness of the walker and the patient's rehabilitation status.

[0071] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for assisting patients with total knee replacement surgery using a hexapod robot as a prototype, characterized in that: The following steps are involved: Step 1: Collect the patient's height and hip height; Step 2: Based on the patient's height and hip joint height, the walker handrail height is dynamically adjusted by controlling the prediction model; Step 3: Identify the terrain environment ahead through the sensor assembly, and enable the walker to execute the procedures of walking on flat ground, climbing steps, and going down stairs.

2. The method for assisting patients with total knee replacement surgery using a hexapod robot as a prototype according to claim 1, characterized in that: The step 2 specifically includes the following steps: The state observer estimates the current state x(k) in real time: x(k+1)=Ax(k)+Bu(k) y(k)=Cx(k) where k is the discrete time index; x(k) = [h(k), Δh(k)] T is the state variable at time k, h(k) represents the current handrail height, Δh(k) represents the rate of change of height, and T represents the matrix transpose; x(k+1) is the state variable at time k+1; u(k) is the control input; y(k) is the system output; matrices A, B, and C represent the state transfer matrix, control input matrix, and output matrix, respectively; The rolling optimizer calculates the optimal value at each sampling time k based on the current state x(k) and the reference trajectory x t (k), rolling optimization of the control sequence {u(k|k),u(k+1|k),...,u(k+P-1)|k} for the next P steps to minimize the performance index J: Among them, Q is the state error weight matrix; R is the control input weight matrix; x(k+i|k) represents the state variable predicted for the next i-th step at the current time k; x i (k+i|k) represents the reference trajectory predicted for the future i-th step at the current time k; u(k+i|k) represents the control input for the future i-th step to be optimized; i = 0, 1, 2, ..., P-1.

3. The method for assisting patients with total knee replacement surgery using a hexapod robot as a prototype according to claim 2, characterized in that: The step 2 further comprises the following steps: The mechanical limit constraint of the rolling optimization process is as follows: h min ≤h(k+i|k)≤h max Among them, h(k+i|k) represents the predicted handrail height of the i-th step in the future at the current time k; h min is the minimum allowed height; h max is the maximum permitted height; The rate constraint is as follows: |Δh(k+i|k)≤Δh max | Where Δh(k+i|k) represents the handrail height adjustment rate; Δh max Indicates the maximum allowable adjustment rate; The comfort threshold is as follows: |Δh(k+i|k)≤δ comfort | Among them, δ comfort Indicates the maximum instantaneous altitude change that the user can accept.

4. The method for assisting patients with total knee replacement surgery using a hexapod robot as a prototype according to claim 1, characterized in that: In step 3, the steps of making the walker perform the step climbing program include: The height tracking of the robot foot is achieved through the proportional-differential control law: Among them, f sty Indicates the output force of the mechanical foot in the vertical direction; h std Indicates the desired height; h st Indicates the actual height of the current mechanical leg; k p represents the proportional coefficient; k d represents the differential coefficient; First, the hexapod robot raises its front legs on both sides synchronously to a height of h. l : h l =h o +h s Among them, h o is the obstacle height; h s is the preset safety distance; f swy is the vertical force of the swinging mechanical foot; h swd is the desired height of the swinging mechanical foot; h sw is the actual height of the swinging mechanical foot; k p is the proportional coefficient; k d is the differential coefficient; h swd The rate of change of altitude; h sw The rate of change of altitude; Then, the middle legs on both sides are driven to rise along the same trajectory, and the movement process is monitored by the infrared sensor to measure the swing amplitude of the patient's lower limbs θ h Perform adaptive adjustment: Δv=K·|θ h -θ m | Among them, Δv represents the change in swing amplitude; θ h Indicates the swing amplitude of the patient's lower limbs; θ m Indicates the preset standard swing; K indicates the adjustment gain coefficient; Finally, control the hind legs on both sides to complete the step-over.

5. The method for assisting patients with walking after total knee replacement surgery using a hexapod robot as a prototype according to claim 1, characterized in that: In step 3, the step of causing the walking aid to execute the procedure of descending stairs includes: First, control the front legs on both sides to touch the next step; Then, the middle legs on both sides are driven to stretch to the next step, and the infrared sensor monitors the swing of the patient's lower limbs and makes adaptive adjustments; Finally, control the hind legs on both sides to retract the support, and in the process of going down the stairs, swing the mechanical foot in the vertical direction to generate the force f swy for: f swy =m·g+F safety Where m is the mass of the mechanical foot; g is the acceleration due to gravity; F safety For extra safety.

6. The method for assisting patients with total knee replacement surgery using a hexapod robot as a prototype according to claim 1, characterized in that: The method also includes step 4, extracting the swing amplitude data of the patient's lower limbs after using the walker, comparing the swing amplitude before and after using the walker, and completing the rehabilitation assessment.

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