A sole sensor-based adaptive speed method for lower extremity exoskeleton

Abstract

This invention provides an adaptive speed method for a lower limb exoskeleton based on a foot sensor. The lower limb exoskeleton has a hip joint that coordinates with the movement of the human hip and a knee joint that coordinates with the movement of the human leg. The method includes: S1: acquiring foot movement data of the lower limb exoskeleton during walking; S2: acquiring the posture of the hip joint during walking; S3: adjusting the output torque of the hip joint and the extension and flexion of the knee joint based on the foot movement data and the posture of the hip joint. This invention discloses an adaptive speed method for a lower limb exoskeleton based on a foot sensor. This method can ensure normal use on the existing control basis, while improving the responsiveness of human-computer interaction, thereby effectively enabling the lower limb exoskeleton to adapt to human speed.

Description

Technical Field

[0001] This invention relates to the field of exoskeletons, and in particular to an adaptive speed method for a lower limb exoskeleton based on a foot sensor. Background Technology

[0002] Wearable exoskeleton robots are robots that achieve motion control through human-computer interaction, and they have a wide range of practical applications in military defense, agricultural production, medical rehabilitation, and industrial production. Exoskeleton robots are wearable mechanical devices designed based on bionics and human process engineering. Due to limitations in human physical strength and fatigue, there are certain limits to the external loads humans can withstand and the range of continuous work. Exoskeleton robots, however, can use sensors to detect the wearer's activity status and, through calculation, control each driven joint, allowing the wearer to withstand a wider range of loads with minimal or no energy depletion, thus assisting the wearer in working for extended periods.

[0003] Current motion control algorithms for lower limb exoskeletons have errors when tracking the desired trajectories of the hip and knee joints. Research teams at the University of California, Berkeley, have developed lower limb exoskeletons using a hybrid control algorithm combining position control and sensitivity amplification control; the University of Tsukuba in Japan has also developed exoskeletons that use bioelectric currents from the skin to determine the wearer's movement intentions and control the exoskeleton robot to move with the wearer; all of these approaches suffer from poor human-machine tracking performance. Summary of the Invention

[0004] The purpose of this invention is to provide an adaptive speed method for lower limb exoskeletons based on plantar sensors, thereby improving the human-machine tracking performance of lower limb exoskeletons.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an adaptive speed method for a lower limb exoskeleton based on a foot sensor, wherein the lower limb exoskeleton has a hip joint that coordinates with the movement of the human hip and a knee joint that coordinates with the movement of the human leg, comprising: S1: acquiring foot movement data of the lower limb exoskeleton during walking; S2: acquiring the posture of the hip joint during walking; S3: adjusting the output torque of the hip joint and the extension and flexion of the knee joint according to the foot movement data and the posture of the hip joint; wherein step S3 includes: S31: calculating the current walking cycle of the human body based on the foot movement data; S32: calculating reference values ​​for the extension and flexion of the knee joint based on the angle of the hip joint at various times during the current walking cycle; S33: determining the output torque of the hip joint in the next walking cycle based on the duration of the current walking cycle, and controlling the activity level of the knee joint of the lower limb exoskeleton at various times during the next walking cycle based on the reference values ​​for the extension and flexion of the knee joint.

[0006] Furthermore, both feet of the lower limb exoskeleton are equipped with sensors that can detect the contact status between the feet of the lower limb exoskeleton and the ground.

[0007] Furthermore, the foot movement data includes the time elapsed from the moment the foot of the lower limb exoskeleton on the same side touches the ground to the next time it leaves the ground.

[0008] Furthermore, the posture of the hip joint includes the angle of the hip joint of the lower limb exoskeleton at various times during a walking state.

[0009] Furthermore, it also includes a relay module, which can convert the pressure value collected by the sensor into a pulse signal.

[0010] Analysis shows that the present invention discloses an adaptive speed method for a lower limb exoskeleton based on a foot sensor. This method can ensure normal use on the existing control basis, while improving the following performance of human-computer interaction, thereby effectively enabling the lower limb exoskeleton to adapt to human speed. Attached Figure Description

[0011] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0012] Figure 1 A flowchart of an embodiment of the present invention. Detailed Implementation

[0013] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. Indeed, those skilled in the art will recognize that modifications and variations can be made to the invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the invention encompass such modifications and variations falling within the scope of the appended claims and their equivalents.

[0014] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected," "linked," and "set up" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a direct connection or an indirect connection through intermediate components; a wired connection, a radio connection, or a wireless communication signal connection. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0015] The accompanying drawings illustrate one or more examples of the invention. The detailed description uses numerals and letters to refer to features in the drawings. Similar or analogous reference numerals in the drawings and description have been used to refer to similar or analogous parts of the invention. As used herein, the terms “first,” “second,” “third,” and “fourth,” etc., are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of a single component.

[0016] like Figure 1As shown, according to an embodiment of the present invention, an adaptive velocity method for a lower limb exoskeleton based on a foot sensor is provided. The lower limb exoskeleton has a hip joint that coordinates with the movement of the human hip and a knee joint that coordinates with the movement of the human leg. The method includes: S1: acquiring foot motion data of the lower limb exoskeleton during walking; S2: acquiring the posture of the hip joint during walking; S3: adjusting the output torque of the hip joint and the extension and flexion of the knee joint based on the foot motion data and the posture of the hip joint during movement. The extension and flexion represent the rotational state of the knee joint. In this scenario, when one foot touches the ground, one knee joint is in an extended state (knee joint rotation keeps the thigh and lower leg approximately in a straight line), and the other knee joint is in a pre-flexed state (knee joint rotation creates a certain angle between the thigh and lower leg); when the other foot leaves the ground, the other knee joint is fully extended (knee joint rotation reaches its limit) and in a supporting state, while the first knee joint is in a flexed state (knee joint rotation creates a larger angle between the thigh and lower leg); step S3 includes: S31: calculating the duration of the current walking cycle based on foot movement data; S 32: Calculate the extension and flexion reference values ​​of the knee joint based on the angle of the hip joint at various moments in the current walking cycle; S33: Determine the output torque of the hip joint of the lower limb exoskeleton in the next walking cycle based on the current walking cycle, and control the activity level of the knee joint of the lower limb exoskeleton at various moments in the next walking cycle based on the extension and flexion reference values ​​of the knee joint. Usually, the extension and flexion of the knee joint are adjusted by changing the angle of the hip joint when switching from single-foot to double-foot contact, so that the knee joint can play a supporting role. This invention uses the duration of the current walking cycle and the posture of the hip joint in the current walking cycle as data basis to predict the posture and walking speed of the human body in the next walking cycle. By adjusting the output torque of the hip joint of the lower limb exoskeleton, its rotation speed is controlled to match the human body's movement speed, so that the lower limb exoskeleton can better cooperate to help the human body move. Furthermore, this method can provide real-time feedback on the working state of the lower limb exoskeleton, continuously adjusting the working state of the lower limb exoskeleton in the next walking cycle based on the data of the previous walking cycle, so that the working state of the lower limb exoskeleton matches the human body's movement state.

[0017] Preferably, both feet of the lower limb exoskeleton are equipped with sensors that can detect the contact state between the feet of the lower limb exoskeleton and the ground. The sensors are usually pressure sensors, which determine the contact state between the feet and the ground by detecting the pressure of the feet.

[0018] Preferably, the foot movement data includes: the time elapsed from the foot touching the ground to the next lift-off on the same side of the lower limb exoskeleton, that is, the time elapsed from the foot touching the ground to the lift-off on one side is the length of the current walking cycle.

[0019] Preferably, the posture of the hip joint of the lower limb exoskeleton includes: the angle of the hip joint at various times when the human body is walking. The angle of the hip joint can accurately reflect the movement state of the human body's lower limbs, thus serving as a basis for adjusting the working state of the lower limb exoskeleton.

[0020] Preferably, it also includes a relay module, which can convert the pressure value collected by the sensor into a pulse signal. The relay module can convert the output signal of the sensor into a pulse signal with a fixed amplitude. During the test, the stability of the lower limb exoskeleton can be tested by sending pulse signals with different trigger frequencies.

[0021] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: The present invention discloses an adaptive speed method for a lower limb exoskeleton based on foot sensors. Building upon existing control methods, the present invention utilizes foot sensors to record the time of foot lift-off and contact with the ground, as well as the angle of the hip joint. By continuously adjusting the predicted walking speed based on existing data regarding the lift-off and contact times, the walking speed is simulated to mimic the walking frequency of the hip joint; simultaneously, the movement of the knee joint is controlled; thereby achieving a state consistent with human movement.

[0022] This method ensures normal operation on the existing control basis while improving the responsiveness of human-computer interaction, thereby effectively enabling the lower limb exoskeleton to adapt to human speed.

[0023] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for adaptive velocity of a lower limb exoskeleton based on plantar sensors, wherein the lower limb exoskeleton has a hip joint that coordinates with the movement of the human hip and a knee joint that coordinates with the movement of the human leg, characterized in that, include: S1: Acquire foot movement data of the lower limb exoskeleton during human walking; S2: Obtain the posture of the hip joint of the human body in the walking state, the posture of the hip joint includes: the angle of the hip joint of the lower limb exoskeleton of the human body at various times in the walking state. S3: Adjust the output torque of the hip joint and the extension and flexion of the knee joint based on foot movement data and the posture of the hip joint; Wherein, S3 includes: S31: Calculate the current walking cycle of the human body based on the foot movement data; S32: Calculate the reference values ​​for the extension and flexion of the knee joint based on the angle of the hip joint at various times during the current walking cycle; S33: Determine the output torque of the hip joint in the next walking cycle based on the duration of the current walking cycle, and control the degree of activity of the knee joint of the lower limb exoskeleton at each moment in the next walking cycle based on the reference values ​​of the extension and flexion of the knee joint.

2. The adaptive velocity method for a lower limb exoskeleton based on a foot sensor according to claim 1, characterized in that, The lower limb exoskeleton is equipped with sensors in both feet, which can detect the contact status between the feet of the lower limb exoskeleton and the ground.

3. The adaptive velocity method for a lower limb exoskeleton based on a plantar sensor according to claim 2, characterized in that, The foot movement data includes the time elapsed from the moment the foot of the lower limb exoskeleton on the same side touches the ground to the next time it leaves the ground.

4. The adaptive velocity method for a lower limb exoskeleton based on a foot sensor according to claim 1, characterized in that, It also includes a relay module, which can convert the pressure value collected by the sensor into a pulse signal.

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