Lower extremity adaptive assistive exoskeleton and assistive method thereof

Abstract

This invention discloses a lower limb adaptive assistive exoskeleton and its assistive method, including a waist binding strap assembly, a leg binding strap, an X-axis motor at the hip joint, a Y-axis motor at the femur, an upper skeleton rod, and a lower skeleton rod. The X-axis motor assists in the forward and backward swinging of the lower limb, and the Y-axis motor assists in the left and right swinging of the lower limb. The X-axis motor and the Y-axis motor are connected by the upper skeleton rod, and the leg binding strap and the Y-axis motor support are connected by the lower skeleton rod. A straight rod-type weighing sensor is installed between the upper end of the X-axis motor and the upper skeleton rod. Utilizing a double crankshaft structure, while maintaining the exoskeleton's motion assistance, a brushless motor provides support for the lateral assistance of the lower limb movement, achieving high-frequency current loop control. This real-time capability can capture transient anomalies during movement and quickly generate reverse constraint forces. FOC improves system energy efficiency by minimizing motor copper and iron losses.

Description

Technical Field

[0001] This invention relates to the field of assistive devices for sports, and in particular to a lower limb adaptive assistive exoskeleton and its assistive method. Background Technology

[0002] With the increasing demand for fitness among the general public, the need for sports assistive devices is growing daily. However, existing sports assistive equipment has many limitations and is unable to meet the broad consumer demand.

[0003] In everyday sports, most knee sprains are caused by incorrect foot positioning upon landing—the vertical ground reaction force from medial deviation causes explosive supination or inverted torque in the joint within a short time (approximately 50 milliseconds). If the lateral outward twisting (valgus) or inward adduction (varus) of the knee joint exceeds physiological limits (valgus > 10°, varus > 5°), it can easily lead to damage to the medial collateral ligament (MCL), lateral collateral ligament (LCL), and meniscus. Existing exoskeleton devices lack active limiting mechanisms for lateral movement, relying solely on rigid structures or passive cushioning devices, which cannot respond dynamically to abnormal movements in real time. Furthermore, some fall protection mechanisms proposed in patents, such as absorbing impact energy through airbags or joint work, do not address the issue of real-time lateral stability during movement. Considering the above, it is believed that this technology requires a protective device capable of dynamically monitoring the lateral movement of the knee joint and actively limiting its amplitude to reduce the risk of sports injuries and improve the safety and reliability of the exoskeleton.

[0004] Based on the above, this invention proposes a lower limb adaptive assistive exoskeleton and its assistive method to effectively solve the above problems. Summary of the Invention

[0005] To address the problems existing in the background art, the present invention provides a lower limb adaptive assistive exoskeleton.

[0006] The present invention adopts the following technical solution: A lower limb adaptive assistive exoskeleton includes a waist binding strap assembly, a leg binding strap, an X-axis motor at the hip joint, a Y-axis motor at the femur, an upper skeleton rod, and a lower skeleton rod. The X-axis motor assists in the forward and backward swinging of the lower limb, and the Y-axis motor assists in the left and right swinging of the lower limb. The X-axis motor and the Y-axis motor are connected by the upper skeleton rod, and the leg binding strap and the Y-axis motor support are connected by the lower skeleton rod. A straight rod-type weighing sensor is provided between the upper end of the X-axis motor and the upper skeleton rod, and a battery assembly is provided on the rear side of the waist binding strap assembly. The straight rod-type weighing sensor is an RML131 sensor.

[0007] Furthermore, the X-axis motor is a servo motor assembly, and the Y-axis motor is a brushless motor assembly.

[0008] Furthermore, the waist binding belt assembly includes a waist binding belt and a fixing belt. The two ends of the front part of the fixing belt are connected to the waist binding belt, and the battery assembly is fixed to the rear side of the middle part of the fixing belt.

[0009] Furthermore, the brushless motor assembly includes a brushless motor upper cover, a brushless motor lower cover, a display screen, and a brushless motor. The brushless motor is fixed between the brushless motor upper cover and the brushless motor lower cover, and the display screen is provided on the front side of the brushless motor upper cover.

[0010] Furthermore, the servo assembly includes a lower servo cover, an upper servo cover, a servo, and an adjusting slider. The servo is fixed in the groove of the lower servo cover, the end of the servo is connected to the upper servo cover, and the upper part of the lower servo cover is connected to the adjusting slider, which is slidably locked onto the fixed belt.

[0011] Furthermore, the upper skeletal members are curved, tapering towards the center from the bottom.

[0012] Furthermore, the lower skeletal members are wavy and curved.

[0013] Furthermore, the waist binding strap is a soft, flat strap with its ends connected by Velcro.

[0014] Furthermore, the waist binding strap is a soft, flat strap woven from a mixture of nylon and TPU.

[0015] Furthermore, the battery assembly includes a battery compartment cover and a battery.

[0016] An assistive method for a lower limb adaptive assistive exoskeleton, the method being implemented through the following steps: Step 1: After the user puts on the device, the system initializes and records data information under the standard standing posture. After the device is put on, the simulated feedback servo outputs an analog signal to the main control module A0 pin to obtain the current position information, such as: hip joint motor position: 80. At the same time, the knee joint brushless motor encoder reads the position information and sets the above read values ​​as the offset. When calculating the motor position later, this offset is subtracted, and the initial body posture parameters are completed. Step 2: Sensor initialization. Record initial muscle strength parameters by raising the leg. After the device is put on, the main control module A3 pin reads the analog signal of the RML131 sensor through the amplified signal, for example: Force: 344. Then, set this reading to a constant (zero). From then on, the serial port reading of the sensor will be positive when raising the leg and negative when lowering it. Step 3: Set the servo motor's swing amplitude using the data collected in Step 2; detect the current force by reading the RML131 analog input and adjust the servo motor position accordingly. Specifically: when the detected force forceIs is greater than the desired forceDesired, the servo motor position decreases (rotates counterclockwise). When the detected force forceIs is less than the desired force forceDesired, the servo motor position increases (rotates clockwise). In this way, the servo motor can automatically adjust its position according to changes in external force, thereby achieving a power assist effect. For example, if this is a control system for a robotic arm, the servo motor can automatically adjust the position of the robotic arm based on the applied force to provide assistance or resistance. Step 4: Determine whether the left and right legs are the supporting legs by comparing the data collected in Step 1. The state where the legs are not lifted is the motor initialization position. During the movement, the two legs will alternately be in the initialization position. The position information is read to determine whether the left and right legs are the supporting legs. Step 5: Read the information from the brushless motor encoder to determine if the body is tilted to the left or right. The position information is read by the brushless motor encoder set at the knee joint. If the position readings of both legs are positive at the same time, the body is judged to be tilted to the left, and vice versa. Step 6: Determine the current user's gait based on the information collected in Steps 4 and 5; after determining the supporting leg, the brushless motor encoder on the knee joint of the supporting leg reads the position information to determine the rotation angle of the knee. For example, the encoder angle is read through the readEncoderAngle function and converted into radians. The safe angle is set within -5° to 10°. If the rotation angle reading exceeds 10°, it is determined to be knee valgus; if the rotation angle reading is below -5°, it is determined to be knee varus. Step 7: Based on the information collected in Step 6, drive the servo motor and brushless motor to adjust their output power and direction to provide assistance; use the checkTriggerCondition function to determine whether the current angle exceeds 10° or is below -5°, then use the returnToInitialPosition function to set the target angle as the initial position, and use the FOC control algorithm to adjust the motor movement so that the motor smoothly returns to the initial position, thereby achieving reverse work at a limited angle.

[0017] An assistive method for a lower limb adaptive exoskeleton determines the user's movement state by analyzing thigh force data, such as whether the body's center of gravity is tilted to the left or right. This analysis primarily relies on dynamic pressure change data collected by force sensors. If the knee's valgus or varus angle exceeds a set safety threshold, the system initiates a protective action. This safety threshold is dynamically adjusted based on the user's specific movement pattern and physiological limits. When protection is needed, the servo motor at the hip joint coordinates to adjust the assist direction, helping the user adjust their center of gravity to a safe position. This process is precisely adjusted by the hip joint servo motor according to commands from the control module. Simultaneously, the brushless motor outputs reverse torque using a field-oriented control (FOC) algorithm to limit the lateral range of motion of the knee joint. Specifically, the encoder collects the motor's position signal in real time to monitor the knee joint's movement state. The control module determines whether the safety threshold has been exceeded based on the signal returned by the encoder. Once the safety threshold is exceeded, the control module instructs the brushless motor to output reverse torque, pulling the knee joint back to its normal range of motion. In certain necessary situations, the system will stop outputting torque and return control of the body to the user, thus ensuring that the user can adjust their posture independently and avoid secondary injury.

[0018] After performing the protective action, the system stops outputting torque and stabilizes the angle, allowing the knee joint to return to its normal range of motion. This allows users to safely continue their activities even after experiencing a potential sprain. The system continuously monitors the user's movement status in real time throughout the entire activity, ensuring continuous protection.

[0019] The hip joint control module mainly consists of a force sensor (straight-bar load cell and INA125P amplifier) ​​and an analog servo motor, used to monitor and adjust the hip joint's motion state. The force sensor is responsible for collecting dynamic pressure changes in the anterior thigh muscle group, while the servo motor adjusts the assist direction according to the controller's instructions. The knee joint control module includes a brushless motor (e.g., FOC brushless motor driver), an encoder (e.g., AS5047P), and an ESP32-S3 controller. The encoder is responsible for collecting the motor's position signal in real time to monitor the knee joint's motion state; the brushless motor outputs reverse torque through the FOC algorithm to limit the lateral movement of the knee joint; the ESP32-S3 controller processes the sensor data and controls the motor's movement. The control module uses an Arduino development board and an ESP32-S3 controller. It can receive signals from sensors (such as force sensor and encoder signals), judge the motion state based on this sensor data, and execute protective actions, thereby achieving real-time monitoring of the entire system and ensuring low-latency response (total latency less than 50ms).

[0020] During exercise, the system limits the lateral range of motion of the knee joint through the coordinated work of brakes and actuators. The specific steps are as follows: First, the system monitors the knee joint's movement in real time; when lateral movement exceeds a safe threshold, the brakes and actuators work together to output reverse torque; energy transfer increases the actuator's torque output, preventing excessive knee joint movement. If the system detects a potential sprain risk, the controller instructs the actuators to perform reverse work. Specifically, the controller monitors the knee joint's movement in real time; once a sprain risk is detected, an emergency mode is triggered; subsequently, a brushless motor outputs reverse torque to pull the knee joint back to its normal range of motion. Furthermore, during exercise, the system actively positions the knee joint using actuators to maximize protection or minimize potential injury. Specific steps include: the controller dynamically adjusts the protection threshold based on the user's movement pattern; the exoskeleton guides the user to an ideal movement state; and when a risk occurs, the actuator modules work together to provide optimal protection. This invention provides a lower limb adaptive assistive exoskeleton and its assistive method: utilizing a double crankshaft structure, while maintaining exoskeleton motion assistance, a brushless motor provides lateral assistance for lower limb movement. Hardware acceleration via the ESP32S3 enables high-frequency current loop control. This real-time capability captures transient anomalies during movement and quickly generates reverse constraint forces. The FOC (Free-Oriented Control) improves system energy efficiency by minimizing motor copper and iron losses. In battery-powered exoskeletons, this extends battery life while reducing motor heat generation, ensuring safety during extended exercise. By dynamically monitoring the knee joint's motion state, and upon detecting a risk of sprain, the brushless motor outputs reverse torque, and the hip joint servo adjusts the assist direction in coordination, thereby actively limiting the lateral range of motion of the knee joint. This system can respond to abnormal motion situations in real time, ensuring that knee joint movement remains within a safe range. This not only reduces the risk of sports injuries but also improves the overall safety and reliability of the exoskeleton. The protection methods employed in this invention include dynamic limitation methods, risk response methods, and positioning protection methods. These methods can achieve maximum effectiveness when used in combination, and can also be used individually to provide different levels of protection. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is an exploded structural diagram of the present invention; Figure 3 This is a schematic diagram of the wearing state of the present invention. Figure 1 ; Figure 4 This is a schematic diagram of the wearing state of the present invention. Figure 2 ; Figure 5 This is a circuit diagram of the present invention; Figure 6 This is a flowchart of the auxiliary method of the present invention.

[0022] The numbers in the diagram represent the following in order: 1-Waist strap; 2-Leg strap; 3-Fixed waist belt; 4-Servo motor lower cover; 5-Servo motor upper cover; 6-Upper skeleton member; 7-Brushless motor upper cover; 8-Lower skeleton member; 9-Brushless motor; 10-Display screen; 11-Battery compartment cover; 12-Battery; 13-Adjustment slider; 14-Servo motor; 15-Straight rod type load cell; 16-Brushless motor lower cover; 20-Ground; 30-Wearer. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] See attached document Figure 1-2 An adaptive lower limb assistive exoskeleton includes a waist restraint belt 1, a leg restraint belt 2, an X-axis motor at the hip joint, a Y-axis motor at the femur, an upper skeletal member 6, and a lower skeletal member. The X-axis motor assists in the forward and backward swinging of the lower limb, and the Y-axis motor assists in the left and right swinging of the lower limb. The X-axis motor and the Y-axis motor are connected by the upper skeletal member 6. The leg restraint belt 2 is connected to the Y-axis motor support via the lower skeletal member. A straight-rod type weighing sensor 15 is installed between the X-axis motor and the upper end of the upper skeletal member 6. A battery assembly is located at the rear of the waist restraint belt 1. The straight-rod type weighing sensor 15 is used to detect the direction of force.

[0025] The X-axis motor is a servo motor assembly, and the Y-axis motor is a brushless motor assembly.

[0026] The waist binding belt 1 assembly includes a waist binding belt 1 and a fixing belt 3. The two ends of the front part of the fixing belt 3 are connected to the waist binding belt 1, and the battery assembly is fixed to the rear side of the middle part of the fixing belt 3.

[0027] The brushless motor 9 assembly includes a brushless motor upper cover 7, a brushless motor lower cover 16, a display screen 10, and a brushless motor 9. The brushless motor 9 is fixed between the brushless motor upper cover 7 and the brushless motor lower cover 16. The display screen 10 is provided on the front side of the brushless motor upper cover 7.

[0028] The servo assembly includes a lower servo cover 4, an upper servo cover 5, a servo 14, and an adjusting slider 13. The servo is fixed in the groove of the lower servo cover 4. The end of the servo 14 is connected to the upper servo cover 5. The upper part of the lower servo cover 4 is connected to the adjusting slider 13, which is slidably locked onto the fixed belt 3.

[0029] The upper skeletal member 6 is curved, tapering towards the center from the bottom, which better conforms to the curves of the human body.

[0030] The lower skeletal member 8 is wavy and curved, which better conforms to the curves of the human body.

[0031] The waist binding strap 1 is a soft, flat strap with its ends connected by Velcro.

[0032] The waist binding strap 1 is a soft, flat strap woven from a mixture of nylon and TPU. Both the upper skeletal member 6 and the lower skeletal member 8 are made of PLA material.

[0033] The battery assembly includes a battery compartment cover 11 and a battery 12.

[0034] Figure 5 This is a circuit diagram of the present invention, in which 20 represents the ground and 30 represents the wearer.

[0035] The brushless motor is controlled by FOC.

[0036] Field-oriented control (FOC) decomposes the stator current of the motor into magnetic field components, achieving precise decoupling control of the motor's magnetic field. In lateral motion protection scenarios, FOC can accurately output reverse torque (adjustable from 0 to 5 Nm) to ensure that the lateral twisting amplitude of the knee joint is limited within safe thresholds (valgus ≤ 8°, adduction ≤ 4°), avoiding exceeding physiological limits.

[0037] The exoskeleton utilizes a double-crankshaft structure to provide lateral assistance for lower limb movements while maintaining exoskeleton motion assistance. The ESP32S3's hardware acceleration, such as the FPU unit, enables high-frequency current loop control (≥20kHz) with a total response latency of <50ms. This real-time capability can capture transient anomalies during movement, such as sudden pressure drops caused by knee valgus, and quickly generate counter-restraint forces. FOC improves system energy efficiency by minimizing motor copper and iron losses. In battery-powered exoskeletons, this extends battery life while reducing motor heat generation, ensuring safety during extended exercise.

[0038] like Figure 3-4 When this device is in use, the wearer's (30) lower limb movements cause the straight-bar weighing sensor to detect force, driving the servo motor to provide forward assistance to the lower limbs. Simultaneously, when the knee joint undergoes lateral deflection, the brushless motor provides both assistance and resistance to stabilize the lower limb movement.

[0039] The fabrication device provided by this invention utilizes a double crankshaft structure to provide lateral assistance for lower limb movement while maintaining exoskeleton movement assistance.

[0040] During operation, the brushless motor detects lower limb movement and performs motion state analysis. A shift in the body's center of gravity occurs, with the knees exhibiting outward and inward rotation. The brushless motor encoder detects this force line deviation, triggering a protection mechanism. The brushless motor then executes its protection action. Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A lower limb adaptive assistive exoskeleton, characterized in that, The device includes a waist binding strap assembly, a leg binding strap, an X-axis motor at the hip joint, a Y-axis motor at the femur, an upper skeletal member, and a lower skeletal member. The X-axis motor assists in the forward and backward swinging of the lower limbs, and the Y-axis motor assists in the left and right swinging of the lower limbs. The X-axis motor and the Y-axis motor are connected by the upper skeletal member, and the leg binding strap is connected to the Y-axis motor bracket by the lower skeletal member. A straight-rod type weighing sensor is installed between the X-axis motor and the upper end of the upper skeletal member, and a battery assembly is installed on the rear side of the waist binding strap assembly.

2. The lower limb adaptive assistive exoskeleton according to claim 1, characterized in that, The X-axis motor is a servo motor assembly, and the Y-axis motor is a brushless motor assembly.

3. The lower limb adaptive assistive exoskeleton according to claim 2, characterized in that, The waist binding belt assembly includes a waist binding belt and a fixing belt. The two ends of the front part of the fixing belt are connected to the waist binding belt, and the battery assembly is fixed to the rear side of the middle part of the fixing belt.

4. The lower limb adaptive assistive exoskeleton according to claim 2, characterized in that, The brushless motor assembly includes a brushless motor upper cover, a brushless motor lower cover, a display screen, and a brushless motor. The brushless motor is fixed between the brushless motor upper cover and the brushless motor lower cover, and the display screen is located on the front side of the brushless motor upper cover.

5. The lower limb adaptive assistive exoskeleton according to claim 3, characterized in that, The servo assembly includes a lower servo cover, an upper servo cover, a servo, and an adjusting slider. The servo is fixed in the groove of the lower servo cover, and the end of the servo is connected to the upper servo cover. The upper part of the lower servo cover is connected to the adjusting slider, which is slidably locked onto the fixed belt.

6. The lower limb adaptive assistive exoskeleton according to claim 1, characterized in that, The upper skeletal structure is curved, tapering towards the center from the bottom.

7. The lower limb adaptive assistive exoskeleton according to claim 1, characterized in that, The lower skeletal members are wavy and curved, and the battery assembly includes a battery compartment cover and a battery.

8. The lower limb adaptive assistive exoskeleton according to claim 3, characterized in that, The waist binding strap is a soft, flat strap with the ends connected by Velcro.

9. A lower limb adaptive assistive exoskeleton according to claim 8, characterized in that, The waist binding strap is a soft, flat band woven from a mixture of nylon and TPU.

10. The assistive method for a lower limb adaptive assistive exoskeleton according to claim 1, characterized in that, The method is implemented through the following steps: Step 1: After the user puts on the device, the system initializes and records data information under the standard standing posture; Step 2: Sensor initialization. Record initial muscle strength parameters by performing a leg raise. Step 3: Set the servo motor's swing amplitude using the data collected in Step 2; Step 4: Determine whether the left and right legs are the supporting legs by comparing the data collected in Step 1. Step 5: Read the information from the brushless motor encoder to determine if the body is tilted to the left or right; Step 6: Determine the current user's gait based on the information collected in Steps 4 and 5; Step 7: Based on the information collected in Step 6, adjust the output power and direction of the servo motor and brushless motor to provide assistance.

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