A haptics-based multi-functional shared control method for prosthetic hands

Abstract

This invention relates to the field of control engineering technology, and in particular to a tactile-based multi-functional shared control method for a prosthetic hand, comprising: S1, real-time acquisition of the user's surface electromyography (EMG) signals, and identification of the user's movement intention based on the EMG signals; S2, determination of the finger to be moved based on the user's movement intention, and judgment of the current availability of the finger to be moved by fingertip tactile readings, determining the movable finger and performing pre-grasping; S3, after pre-grasping, controlling the movable finger to perform stable grasping by calculating the rate of change of gripping force of each finger at adjacent moments; S4, after stable grasping, adjusting the gripping force level by executing a target activation gesture, thus completing the control of the prosthetic hand. This invention enables stable grasping of the prosthetic hand, as well as in-hand operation and multi-grasping control with one hand.

Description

Technical Field

[0001] This invention relates to the field of control engineering technology, and in particular to a tactile-based multi-functional shared control method for a prosthetic hand. Background Technology

[0002] Due to limited hand function and a heavy control burden, prosthetic hands have a high abandonment rate among amputees, highlighting the gap between clinical application and laboratory techniques. Therefore, shared control technology can help provide a solution for prosthetic hands that balances control burden and control accuracy. Currently, there are differing opinions on what functions should be introduced into the control of prosthetic hands using shared control technology, and a comprehensive shared control approach that can adapt to diverse daily life tasks is lacking. Summary of the Invention

[0003] The purpose of this invention is to provide a tactile-based multi-functional shared control method for prosthetic hands. Based on real-time tactile readings and preset thresholds, the method enables compliant and stable grasping of the prosthetic hand; by autonomously judging the availability of fingers, it realizes the anthropomorphic function of the prosthetic hand grasping multiple objects at one time; and based on the rate of change of grasping force at adjacent moments, it determines a specific grasping force threshold for an object, and realizes autonomous adjustment of the grasping force level according to the user's wishes.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] A tactile-based method for multifunctional shared control of a prosthetic hand, comprising:

[0006] S1. Real-time acquisition of the user's surface electromyography (EMG) signals, and recognition of the user's movement intention based on the surface EMG signals;

[0007] S2. Determine the finger to be moved based on the user's movement intention, and judge the current availability of the finger to be moved by the fingertip tactile reading, determine the movable finger and perform pre-grabbing;

[0008] S3. After performing the pre-grasping, the movable fingers are controlled to perform stable gripping by calculating the rate of change of gripping force of each finger at adjacent moments.

[0009] S4. After achieving the stable grip, adjust the grip strength level by executing the target activation gesture to complete the control of the prosthetic hand.

[0010] Preferably, in step S1, the real-time acquisition of the user's surface electromyography (EMG) signals and the identification of the user's movement intention based on the EMG signals include:

[0011] Surface electromyography (EMG) sensors were placed on a pair of antagonistic muscles in the user's forearm to collect the user's surface EMG signals in real time.

[0012] The surface electromyography (EMG) signal is filtered, rectified, and normalized, and the processed EMG signal is mapped into a control signal.

[0013] Preferably, mapping the processed signal into a control signal includes:

[0014]

[0015] Where K is the gain coefficient, EMG(t) is the processed surface electromyography signal, Output is the output control signal, and EMG(min) and EMG(max) are the minimum and maximum thresholds of the surface electromyography signal, respectively.

[0016] Preferably, in step S2, determining the current availability of the finger to be moved based on the fingertip tactile reading, identifying the movable finger, and pre-grabbing includes:

[0017] The fingertip tactile readings of the finger that needs to move are monitored in real time and compared with a preset tactile threshold. If the readings are greater than or equal to the preset tactile threshold, the finger is determined to be occupied; if the readings are less than the preset tactile threshold, the finger is determined to be movable.

[0018] The movable fingers are controlled to perform a first-stage flexion movement until the fingertip tactile readings of all movable fingers reach the preset tactile threshold, thus completing the pre-grasping.

[0019] Preferably, in step S3, controlling the movable fingers to perform stable gripping by calculating the rate of change of gripping force of each finger at adjacent moments includes:

[0020] After the pre-grasp is completed, all movable fingers are controlled to perform the second stage of flexion movement, and the rate of change of gripping force of each movable finger at adjacent moments is calculated in real time. When the rate of change of gripping force of the movable finger at adjacent moments reaches the preset gripping threshold, the second stage of flexion movement is stopped until all movable fingers stop the second stage of flexion movement, thus completing the stable grip.

[0021] Preferably, calculating the rate of change of grip force of the movable finger at adjacent time points includes:

[0022]

[0023] Where β is the rate of change of grip strength between adjacent time points, and F t For gripping force at time t, F t-1 Let t-1 be the gripping force.

[0024] Preferably, in step S4, adjusting the grip strength level by executing a target activation gesture to control the prosthetic hand includes:

[0025] After achieving a stable grip, record the current fingertip tactile reading F. i Recorded as stable grip force F S At this time, F i =F S ;

[0026] Adjust the grip strength level by performing the first target activation gesture, then proceed to the third stage of flexion movement until F. i =2·F S ;

[0027] Adjust the grip strength level by performing the second target activation gesture, and then perform stretching exercises until F. i =F S The intra-hand operation of the prosthetic hand is completed.

[0028] Preferably, the method further includes:

[0029] After completing the stable grip, if the user needs to grasp another object while retaining the object in their hand, they can perform another grip gesture by performing S2-S3 to complete the stable grip on the other object.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention proposes a tactile-based multi-functional shared control method for prosthetic hands. Based on fingertip tactile perception, it improves the operational performance and user experience of the prosthetic hand through signal processing. Based on contact state analysis, it autonomously judges the availability of fingers to realize the multi-grasping function of a human-like hand. Based on real-time monitoring of gripping force, it enables the prosthetic hand to smoothly and stably grasp target objects and allows users to adjust the gripping force level to complete in-hand operations based on stable gripping. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart of a tactile-based multi-functional shared control method for a prosthetic hand according to an embodiment of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] This embodiment provides a tactile-based multi-functional shared control method for a prosthetic hand, such as... Figure 1 As shown, it includes:

[0037] S1. Real-time acquisition of the user's surface electromyography (EMG) signals, and recognition of the user's movement intention based on the surface EMG signals;

[0038] S2. Determine the finger to be moved based on the user's movement intention, and judge the current availability of the finger to be moved by the fingertip tactile reading, determine the movable finger and perform pre-grabbing;

[0039] S3. After performing the pre-grasping, the movable fingers are controlled to perform stable gripping by calculating the rate of change of gripping force of each finger at adjacent moments.

[0040] S4. After achieving the stable grip, adjust the grip strength level by executing the target activation gesture to complete the control of the prosthetic hand.

[0041] Specifically, this embodiment identifies the contact state between fingers and objects to obtain the occupancy state of each finger, enabling autonomous judgment of finger availability and completing pre-forming of gripping and multi-handed grasping; by analyzing the rate of change of gripping force, it obtains the force interaction information between fingers and objects, enabling autonomous judgment of the force closure of grasping objects and recording specific gripping force thresholds of objects; based on the autonomously recorded specific gripping force thresholds of objects, through real-time monitoring of gripping force, it enables users to autonomously adjust the gripping force level and ensure that objects are not damaged (when the gripping force level is increased) or not dropped (when the gripping force level is decreased).

[0042] The method for designing a novel shared control strategy includes: using a threshold method to determine finger availability and initial contact with an object based on real-time fingertip tactile readings; using a threshold method to determine when stable gripping of an object is achieved based on the calculation of the rate of change of gripping force at adjacent moments, and simultaneously recording the current tactile readings of each finger as the object-specific stable gripping force threshold; and adjusting fingertip tactile readings in real time by controlling finger movement based on the object-specific stable gripping force threshold, thereby enabling autonomous adjustment of the gripping force level according to the user's wishes.

[0043] Further, in step S1, the real-time acquisition of the user's surface electromyography (EMG) signals, and the identification of the user's movement intention based on the EMG signals, includes:

[0044] Surface electromyography (EMG) sensors were placed on a pair of antagonistic muscles in the user's forearm to collect the user's surface EMG signals in real time.

[0045] The surface electromyography (EMG) signal is filtered, rectified, and normalized, and the processed EMG signal is mapped into a control signal.

[0046] Mapping the processed signal into a control signal includes:

[0047]

[0048] Where K is the gain coefficient, EMG(t) is the processed surface electromyography signal, Output is the output control signal, and EMG(min) and EMG(max) are the minimum and maximum thresholds of the surface electromyography signal, respectively.

[0049] Specifically, in this embodiment, two surface electromyography (SEMG) sensors are placed on a pair of antagonistic muscles in the user's forearm to acquire real-time SEMG signals. The SEMG signals are then subjected to a series of preprocessing steps, including filtering and rectification, and normalized to the range of 0-1. Finally, they are linearly or nonlinearly mapped to the speed of a motor to control the prosthetic hand to perform different movements.

[0050] If the surface electromyography (EMG) signal acquired and preprocessed by the sensor is known to be EMG(t), the relationship between the control signal and the input surface EMG signal is as follows: Where K is the gain coefficient, which can be adjusted according to the user's actual situation.

[0051] Further, in step S2, determining the current availability of the finger to be moved based on the fingertip tactile reading, identifying the movable finger, and performing pre-grabbing includes:

[0052] The fingertip tactile readings of the finger that needs to move are monitored in real time and compared with a preset tactile threshold. If the readings are greater than or equal to the preset tactile threshold, the finger is determined to be occupied; if the readings are less than the preset tactile threshold, the finger is determined to be movable.

[0053] The movable fingers are controlled to perform a first-stage flexion movement until the fingertip tactile readings of all movable fingers reach the preset tactile threshold, thus completing the pre-grasping.

[0054] Specifically, based on the user's movement intention identified by S1, the finger that needs to be moved is determined. Real-time monitoring of fingertip tactile readings is then compared with a preset threshold to determine if the finger is currently occupied. For example, if the current tactile reading of the i-th finger is F... i (i = 1, 2, ..., 5), with a preset threshold of F. T When F i ≥F T If the finger is occupied, it will not perform any movement; otherwise, the unoccupied finger will flex according to the user's intention. The movement will continue until the fingertip tactile intensity reaches a preset threshold F. T When the tactile readings of all moving fingers reach the preset threshold F, the moving fingers will stop moving. T At that time, the prosthetic hand completes the pre-grasp of the object.

[0055] Furthermore, in step S3, controlling the movable fingers to perform stable grasping by calculating the rate of change of gripping force of each finger at adjacent moments includes:

[0056] After the pre-grasp is completed, all movable fingers are controlled to perform the second stage of flexion movement, and the rate of change of gripping force of each movable finger at adjacent moments is calculated in real time. When the rate of change of gripping force of the movable finger at adjacent moments reaches the preset gripping threshold, the second stage of flexion movement is stopped until all movable fingers stop the second stage of flexion movement, thus completing the stable grip.

[0057] The calculation of the rate of change of grip force of the movable finger at adjacent moments includes:

[0058]

[0059] Where β is the rate of change of grip strength between adjacent time points, and F t For gripping force at time t, F t-1 Let t-1 be the gripping force.

[0060] Specifically, after the prosthetic hand completes the pre-grasp of the object based on contact state recognition, all moving fingers will be reactivated and continue flexion movements. At this time, the rate of change of gripping force for each finger at adjacent time points will be calculated. and preset threshold β t A comparison is made to determine whether the prosthetic hand has achieved a stable grasp of the object. If the prosthetic hand has successfully grasped the object, the tactile readings of each finger at the current moment will be automatically recorded as the object-specific grasping force threshold.

[0061] Furthermore, in step S4, adjusting the grip strength level by executing a target activation gesture to control the prosthetic hand includes:

[0062] After achieving a stable grip, record the current fingertip tactile reading F. iRecorded as stable grip force F S At this time, F i =F S ;

[0063] The third stage of flexion is performed by executing the first target activation gesture until F. i =2·F S ;

[0064] Perform the stretching movement by executing the second target activation gesture until F i =F S The intra-hand operation of the prosthetic hand is completed.

[0065] Specifically, after the prosthetic hand achieves a stable grasp of an object by calculating the rate of change in grip force between adjacent moments, the user's specific activation gesture will adjust the grip force level, enabling the prosthetic hand to perform intra-hand manipulation of the object. For example, after the prosthetic hand has achieved a stable grasp of the object, the tactile reading of the moving finger should be F. i =F S F S Based on the stable grip strength threshold obtained in S3, the user's specific activation gesture will cause the moving finger to continue flexion until F. i =2·F S Based on this, if the user performs a specific activation gesture again, the moving finger will extend until F. i =F S .

[0066] Furthermore, the method also includes:

[0067] After completing the stable grip, if the user needs to grasp another object while retaining the object in their hand, they can perform another grip gesture by performing S2-S3 to complete the stable grip on the other object.

[0068] Specifically, after the prosthetic hand has successfully grasped an object, if the user wishes to grasp another object while keeping the object in their hand, they can directly execute another grasping gesture. Based on the autonomous judgment of finger availability, the prosthetic hand will perform multiple grasping operations and repeat S2-S3 until a stable grasp of the second object is achieved.

[0069] This embodiment proposes a tactile-based multi-functional shared control method for a prosthetic hand. Based on fingertip tactile perception, it improves the operational performance and user experience of the prosthetic hand through signal processing. Based on contact state analysis, it autonomously judges the availability of fingers to realize the multi-grasping function of a human-like hand. Based on real-time monitoring of gripping force, it enables the prosthetic hand to smoothly and stably grasp target objects and allows users to adjust the gripping force level to complete in-hand operations based on stable gripping.

[0070] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A tactile-based multi-functional shared control method for a prosthetic hand, characterized in that, include: S1. Real-time acquisition of the user's surface electromyography (EMG) signals, and recognition of the user's movement intention based on the surface EMG signals; S2. Determine the finger to be moved based on the user's movement intention, and judge the current availability of the finger to be moved by the fingertip tactile reading, determine the movable finger and perform pre-grabbing, including: The fingertip tactile readings of the finger that needs to move are monitored in real time and compared with a preset tactile threshold. If the readings are greater than or equal to the preset tactile threshold, the finger is determined to be occupied; if the readings are less than the preset tactile threshold, the finger is determined to be movable. The movable fingers are controlled to perform a first-stage flexion movement until the fingertip tactile readings of all movable fingers reach the preset tactile threshold, thus completing the pre-grasping; S3. After performing the pre-grasping, the movable fingers are controlled to perform stable gripping by calculating the rate of change of gripping force of each finger at adjacent moments, including: After the pre-grasp is completed, all movable fingers are controlled to perform the second stage of flexion movement, and the rate of change of gripping force of each movable finger at adjacent moments is calculated in real time. When the rate of change of gripping force of the movable finger at adjacent moments reaches the preset gripping threshold, the second stage of flexion movement is stopped until all movable fingers stop the second stage of flexion movement, thus completing the stable grip. S4. After achieving the stable grip, adjust the grip strength level by executing the target activation gesture to complete the control of the prosthetic hand, including: After achieving a stable grip, record the current fingertip tactile reading. F i Recorded as stable grip strength F S ,at this time ; Adjust the grip strength level by performing the first target activation gesture, then proceed to the third stage of flexion movement, until... ; Adjust the grip strength level by performing the second target activation gesture, and then perform stretching exercises until... The intra-hand operation of the prosthetic hand is completed.

2. The tactile-based multi-functional shared control method for a prosthetic hand according to claim 1, characterized in that, In step S1, the user's surface electromyography (EMG) signals are collected in real time, and the user's movement intention is identified based on the surface EMG signals, including: Surface electromyography (EMG) sensors were placed on a pair of antagonistic muscles in the user's forearm to collect the user's surface EMG signals in real time. The surface electromyography (EMG) signal is filtered, rectified, and normalized, and the processed EMG signal is mapped into a control signal.

3. The tactile-based multi-functional shared control method for a prosthetic hand according to claim 2, characterized in that, Mapping the processed signal into a control signal includes: ； in, K This is the gain coefficient. EMG(t) The processed surface electromyography signal, For the output control signal, and These are the minimum and maximum threshold values ​​for surface electromyography (EMG) signals, respectively.

4. The tactile-based multi-functional shared control method for a prosthetic hand according to claim 1, characterized in that, Calculating the rate of change of grip strength of the movable finger at adjacent time points includes: ； in, The rate of change of grip strength between adjacent time points. For grip strength at time t, Let t-1 be the gripping force.

5. The tactile-based multi-functional shared control method for a prosthetic hand according to any one of claims 1-4, characterized in that, The method further includes: After completing the stable grip, if the user needs to grasp another object while retaining the object in their hand, they can perform another grip gesture by performing S2-S3 to complete the stable grip on the other object.

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