Parallel ankle rehabilitation robot and control method thereof

A rehabilitation robot, ankle joint technology, applied in gymnastics equipment, passive exercise equipment, sports accessories, etc., can solve the problems of poor compliance, limited rehabilitation effect, small range of motion, etc., to ensure flexibility and continuity, improve rehabilitation Training effect, improve the effect of active participation

Active Publication Date: 2015-12-02
张明明
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AI-Extracted Technical Summary

Problems solved by technology

[0003] Most of the existing ankle rehabilitation robots use rigid drive mechanisms as drives, such as linear motors or motors. Due to the rigid nature of the drive, this kind of robot has poor compliance, and it is easy to generate uncontrollable forces in the robot control, which is harmful to patients. Bring recovery discomfort and even secondary injury
In addition, the rotation center (main movement) of many ankle-joint robots is inconsistent with the rotation center of the human ankle. During the training process, other parts of the lower limbs will move along with it, not just the ankle joint, so effective training of the ankle joint cannot be guaranteed.
At the same time, the adjustable range of motion of most ankle joint rehabilitation robots is very small, and can only achieve two degrees of freedom of movement, which cannot meet the training postures required by different patients and the full range of rehabilitation needs for ankle...
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Method used

In addition, also can set up rotation angle sensor, be used to detect the motion angle of each kinematic connecting rod, be provided with the first rotation angle sensor in the second bearing 31, be provided with the second rotation angle sensor in the 4th bearing 5, The fifth bearing 33 is provided with a third rotation angle sensor. The rotation angle sensor includes a magnet end and a chip end, and is a well-known product, which will not be described in detail here. Wherein, the magnet end of the first rotation angle sensor is installed on the end in the second bearing 31 of the first movement rod 4 inserted main rod 9 rear ends, and the chip end of the first rotation angle sensor is installed in the second bearing cover 30 The magnet end of the second angle of rotation sensor is installed on the end in the fourth bearing 5 on the second motion bar 3 inserted on the first motion bar 4, and the chip end of the second angle of rotation sensor is installed in the fourth bearing cover 51 The magnet end of the third rotation angle sensor is installed in the fifth bearing 33 on the second movement bar 3 inserted on the third movement bar 25 rear end, and the chip end of the third rotation angle sensor is installed in the fifth bearing cover 32. The movement angles of the three movement rods are monitored in real time through the three rotation angle sensors, that is, the movement angles of the patient are monitored, which improves the rehabilitation training effect of the robot.
In addition, the sensor tray 21 can also be set on the third movement bar 25, the sensor tray 21 is connected with the six-axis force sensor 19 and can be locked by screws, and the movement platform 24 can be locked in the third movement by screws. on rod 25. Through this motion mechanism, the three-degree-of-freedom (dorsiflexion/plantarflexion, varus/valgus, and adduction/abduction) movement of the robot is realized, which can effectively control the distance between the foot plate and the ankle joint, and improve Improve the rehabilitation effect and adaptability of the robot, and through the adjustment of the range of motion, it can adapt to the use of different patients, and the applicability is more extensive.
In order to facilitate installation, the first sleeve 14 is connected with the pneumatic muscle 15, the first cross universal joint coupling 13 in a threaded connection mode, and the second sleeve 18 is threaded with the pneumatic muscle 15 and the tension sensor 20 The tension sensor 20 is connected with the second universal joint coupling 23 in a threaded manner. The first bearing 12 is installed in the connecting rod 11, and a corresponding bearing cover can be installed on the connecting rod 11 to ensure that the first bearing can be stably arranged in the connecting rod, and the bearing cover can be locked by corresponding screws. For the installation of the first cross universal joint coupling and the second cross universal joint coupling, corresponding baffle plates and screws can be used for locking and fixing. Of course, other ways can also be used, as long as the first cross universal joint coupling and the second cross universal joint coupling can be stably connected with the first bearing and the motion mechanis...
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Abstract

The invention discloses a parallel ankle rehabilitation robot and a control method. The parallel ankle rehabilitation robot comprises a base, a driving mechanism and a motion mechanism, wherein the base is provided with a supporting frame in an inserting way; the supporting frame is movably provided with an adjusting mechanism in a clamping way; the adjusting mechanism comprises a main rod, a front arm rod and a leg supporting rod; the front end of the main rod is hinged to the front arm rod; the leg supporting rod is connected with the main rod; the front arm rod is provided with a connecting rod; the main rod is in movable clamping arrangement with the supporting frame; pneumatic muscle or a linear motor is used as a driver; the front end of the driving mechanism is connected with the connecting rod in the adjusting mechanism; the tail end of the driving mechanism is connected with the motion mechanism; the motion mechanism is in movable clamping arrangement with the rear end of the main rod. According to the parallel ankle rehabilitation robot disclosed by the invention, a motion range can be adjusted, so that the parallel ankle rehabilitation robot can adapt to different users for use, and three-DOF (Degree of Freedom) motion training of ankle joints can be covered; since the pneumatic muscle is adopted as the driver, the parallel ankle rehabilitation robot has the advantages of good flexibility, high adaptability and the like.

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  • Parallel ankle rehabilitation robot and control method thereof
  • Parallel ankle rehabilitation robot and control method thereof
  • Parallel ankle rehabilitation robot and control method thereof

Examples

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Example Embodiment

[0039] In order to facilitate the understanding of those skilled in the art, the present invention will be further described below in conjunction with the accompanying drawings.
[0040] as attached Figure 1~5 As shown, one aspect of the present invention discloses a parallel ankle joint rehabilitation robot, including a base 2, a support frame 7 is inserted on the base 2, and an adjustment mechanism is movable on the support frame 7, and the adjustment mechanism includes a main rod 9. The forearm rod 10 and the leg support rod 16, the front end of the main rod 9 is connected to the forearm rod 10, the leg support rod 16 is connected to the main rod 9, and the leg support rod 16 is generally attached to the main rod 9 In the middle position, the forearm rod 10 is equipped with a connecting rod 11, and the main rod 9 is movably clamped with the support frame 7; it also includes an adjustment mechanism and a movement mechanism, the front end of the driving mechanism is connected to the connecting rod 11 in the adjustment mechanism, and the end of the driving mechanism is connected to The kinematic mechanism is connected, and the kinematic mechanism and the rear end of the main rod 9 are movable and clamped. During specific installation, part of the forearm rod 10 is inserted into the main rod 9, and a screw knob is installed on the main rod 9, and the screw knob locks the part of the forearm rod 10 located in the main rod 9, so that the forearm rod 10 It is firmly connected with the main rod 9. One end of the connecting rod 11 is inserted into the forearm rod 10, and the forearm rod 10 is provided with a screw knob, which locks the part of the connecting rod 11 located in the forearm rod 10, so that the connecting rod 11 is fixedly connected with the forearm rod 10 . Loosen the screw knob to adjust the installation length of the connecting rod or the forearm. After adjusting to a suitable length, tighten the screw knob to fix the connecting rod and the forearm rod, or fix the forearm rod and the main rod. Easy to operate.
[0041] In addition, in order to effectively control the vertical telescopic range of the robot and improve the adaptability of the robot, the support frame and the base can be installed in a telescopic form. By setting the limit groove 71 on the support frame 7 and the screw knob on the base 2, the screw knob is locked from the side wall of the base 2 and inserted into the limit groove 71 of the support frame 7, and then continue to tighten to support The frame is locked with the base, thereby realizing the fixed connection between the support frame and the base. When the height of the support frame needs to be adjusted, loosen the screw knob, lift or sink the support frame, and then tighten the screw knob to securely connect the support frame to the base after meeting the height requirement, which is very convenient to operate.
[0042] An angle positioning mechanism is provided between the main rod 9 and the support frame 7, and the angle positioning mechanism includes an adjusting handle 29, a front fixing piece 283, a front toothed positioning piece 281, a rear toothed positioning piece 282, a rear fixing piece 284 and fastening bolts 27, the front fixed piece 283 is clamped on the front toothed positioning piece 281, the rear fixed piece 284 is clamped on the rear toothed positioning piece 282, and the fastening bolt 27 is from the front fixed piece 283, the front toothed positioning piece 281, the rear belt The tooth spacer 282 and the rear fixed piece 284 pass through, and the adjustment handle 19 is sleeved on the fastening bolt 27 and locked so that the front tooth spacer 281 and the rear tooth spacer 282 are engaged and installed, and the main rod 9 is fixed to the front by screws. The sheet 283 is connected, and the support frame 7 is connected with the rear fixing sheet 284 by screws. The adjustment handle 19 is connected with the fastening bolt in a threaded connection, and the handle part of the adjustment handle is exposed outside the support frame. The thread is equivalent to playing the role of a "nut", and the difference is that it has a handle for easy operation. Concave-convex teeth are all arranged on the front fixed piece and the rear fixed piece, and the front fixed piece is connected with the front toothed positioning piece through the concave-convex teeth on it, and the rear fixed piece is connected with the rear toothed spacer through the concave-convex teeth on it. The fixed connection can be realized in other ways, such as locking with screws, etc., which will not be listed here.
[0043] During use, the front fixing piece 283 and the front toothed positioning piece 281 are kept attached and installed, and the rear fixed piece 284 is also kept attached and installed with the rear toothed positioning piece 282 . Because the rear fixed piece 284 is fixedly connected with the support frame 7, and the front fixed piece 283 is fixedly connected with the main rod 9, therefore, after the angle is determined, the front belt positioning piece and the rear toothed positioning piece are engaged and installed, and then Lock the adjustment handle to ensure that the front toothed positioning piece and the rear toothed positioning piece are firmly fitted and installed. When it is necessary to readjust the angle, unscrew the adjustment handle, at this time, the front toothed positioning piece and the rear toothed positioning piece are separated from each other, and the rotation is active. The main rod drives the front toothed positioning piece to rotate a certain angle. The toothed positioning piece is meshed with the rear toothed positioning piece, and then the adjustment handle is locked to ensure a tight installation and achieve the purpose of adjusting the angle of the main rod. Through the angle positioning mechanism, the angle of the main rod can be adjusted and positioned, the rotation range of the robot can be effectively controlled, and the adaptability of the robot is improved.
[0044] The driving mechanism includes a pneumatic muscle 15, a first sleeve 14, a first cross universal joint coupling 13, a second sleeve 18, a tension sensor 20 and a second cross universal joint coupling 23, the first set The barrel 14 is connected to the front end of the pneumatic muscle 15, the first cross universal joint coupling 13 is connected to the first sleeve 14, the second sleeve 18 is connected to the rear end of the pneumatic muscle 15, and one end of the tension sensor 20 is connected to the first sleeve 14. The second sleeve 18 is connected, the other end is connected with the second cross universal joint coupling 23, the first cross universal joint coupling 13 is connected with the connecting rod 11 through the first bearing 12, and the second cross universal joint coupling The shaft device 23 is connected to the motion mechanism through the third bearing 22. Of course, the pneumatic muscle can also be replaced by a linear motor or a cylinder. In this embodiment, the pneumatic muscle is selected as the driver, and the pneumatic muscle is taken as an example for illustration.
[0045] For ease of installation, the first sleeve 14 is threadedly connected to the pneumatic muscle 15 and the first cross joint coupling 13, and the second sleeve 18 is threaded to the pneumatic muscle 15 and the tension sensor 20. , The tension sensor 20 is attached to the second cross universal joint coupling 23 in a threaded manner. The first bearing 12 is installed in the connecting rod 11, and a corresponding bearing cover can be installed on the connecting rod 11 to ensure that the first bearing can be stably arranged in the connecting rod, and the bearing cover can be locked by corresponding screws. For the installation of the first cross universal joint coupling and the second cross universal joint coupling, corresponding baffle plates and screws can be used for locking and fixing. Of course, other ways can also be used, as long as the first cross universal joint coupling and the second cross universal joint coupling can be stably connected with the first bearing and the motion mechanism. In the present invention, the flexibility of the robot when assisting the patient in rehabilitation is improved by adopting the pneumatic muscle, and then matching with the cross universal joint coupling to transmit power.
[0046] Described kinematic mechanism comprises the first kinematic bar 4, the second kinematic bar 3, the 3rd kinematic bar 25, motion platform 24, six-axis force sensor 19 and foot plate 17, and main bar 9 rear end is provided with second bearing 31 and the second bearing 31. Two bearing caps 30, the end of the first movement rod 4 is clamped in the second bearing 31, the first movement rod 4 is provided with the fourth bearing 5 and the fourth bearing cover 51, the second movement rod 3 front ends are clamped on In the fourth bearing 5, a fifth bearing 33 and a fifth bearing cover 32 are installed on the rear end of the second movement rod 3, and the rear end of the third movement rod 25 is clamped in the fifth bearing 33, and the movement platform 24 and the six-axis The force sensor 19 is sequentially set on the third movement rod 25 from bottom to top, the foot plate 17 is installed on the front end of the third movement rod 25, the movement platform 24 is provided with a third bearing 22 and a third bearing cover 221, the third The bearing cover 221 is locked on the motion platform 24 by screws, and the second universal joint coupling 23 is connected to the third bearing 22 . Wherein, the second bearing 31 is usually contained in the rear end of the main rod 9, and the second bearing cover 30 is fixed on the rear end of the main rod 9 by screws and covers the second bearing 31. The end of the first moving rod 4 is generally arranged There is a shaft which is inserted into the second bearing 31 so that the first moving rod can rotate relative to the main rod. Similarly, the fourth bearing 5 is also arranged in the first moving rod 4, and the fourth bearing cover 51 is mounted on the first moving rod 4 by screws and covers the first bearing 5, and the front end of the second moving rod 3 is clipped into The relative rotation between the front end of the second moving rod 3 and the first moving rod 4 is realized in the fourth bearing 5 . And the fifth bearing 33 is also generally arranged in the second moving rod 3 rear ends, the fifth bearing cover 32 is locked on the second moving rod rear end by screws and covers the fifth bearing, and the third moving rod rear end is clamped on The relative movement between the third movement rod and the second movement rod is realized in the fifth bearing. It should be noted that the setting of the number of bearings can be flexibly selected according to actual needs and structural conditions. For example, one bearing or two bearings can be set separately in the corresponding position. This is a conventional choice and will not be detailed here. repeat.
[0047] In addition, the sensor tray 21 can also be set on the third movement rod 25, the sensor tray 21 is connected with the six-axis force sensor 19 and can be locked by screws, and the movement platform 24 can be locked on the third movement rod 25 by screws . Through this motion mechanism, the three-degree-of-freedom (dorsiflexion/plantarflexion, varus/valgus, and adduction/abduction) movement of the robot is realized, which can effectively control the distance between the foot plate and the ankle joint, and improve Improve the rehabilitation effect and adaptability of the robot, and through the adjustment of the range of motion, it can adapt to the use of different patients, and the applicability is more extensive.
[0048] In addition, a rotation angle sensor can also be added to detect the movement angle of each moving link. The second bearing 31 is provided with a first rotation angle sensor, the fourth bearing 5 is provided with a second rotation angle sensor, and the fifth bearing 5 is provided with a second rotation angle sensor. 33 is provided with a third rotation angle sensor. The rotation angle sensor includes a magnet end and a chip end, and is a well-known product, which will not be described in detail here. Wherein, the magnet end of the first rotation angle sensor is installed on the end in the second bearing 31 of the first movement rod 4 inserted main rod 9 rear ends, and the chip end of the first rotation angle sensor is installed in the second bearing cover 30 The magnet end of the second angle of rotation sensor is installed on the end in the fourth bearing 5 on the second motion bar 3 inserted on the first motion bar 4, and the chip end of the second angle of rotation sensor is installed in the fourth bearing cover 51 The magnet end of the third rotation angle sensor is installed in the fifth bearing 33 on the second movement bar 3 inserted on the third movement bar 25 rear end, and the chip end of the third rotation angle sensor is installed in the fifth bearing cover 32. The movement angles of the three movement rods are monitored in real time through the three rotation angle sensors, that is, the movement angles of the patient are monitored, which improves the rehabilitation training effect of the robot.
[0049] It should be noted that the above-mentioned second bearings, third bearings, first sleeves, second sleeves, etc., have the same structure and belong to the same type of components, and are defined as second bearings only for the convenience of explanation. , the third bearing, the first sleeve, the second sleeve, etc., are not particularly limited herein.
[0050] In addition, in the present invention, two main rods are symmetrically arranged on the left and right sides of the support frame, and a driving mechanism is respectively installed at both ends of the forearm rod on each main rod, that is, there are four driving mechanisms in total. It also has four pneumatic muscles. The distance between two pneumatic muscles on the same side is generally 250mm to 350mm. For the foot plate, a certain distance can also be adjusted, and the adjustment range is generally set from 0mm to 20mm. The motion platform can also be adjusted up and down, and the adjustment range is generally set from 0mm to 100mm. The distance between the foot plate and the motion platform is usually 0mm to 120mm, the adjustable range of the forearm rod is 0mm to 100mm, the adjustable range of the connecting rod is 0mm to 50mm, and the adjustable range of the support frame is 0mm to 300mm. The dorsiflexion/plantarflexion range that this robot can achieve is 40°/50°. The varus/valgus range that this robot can achieve is 40°/20°. The adduction/abduction range that this robot can achieve is 20°/20°.
[0051] The detailed movement process is as follows:
[0052]First, the patient places the injured foot on the foot plate and fixes it so that the movement axis of the patient's ankle is aligned with the movement center of the second bearing in the movement platform of the present invention. Then start the robot and start training. First, the pneumatic muscles start to move according to the preset trajectory. The lower end of the pneumatic muscles drives the motion platform to move, and the motion platform will perform corresponding echoing motions according to the corresponding contraction and stretching of the four pneumatic muscles. The third movement The rod also moves accordingly. And the first bearing 12 and the first cross cardan coupling 13 driven by the upper end of the pneumatic muscle perform corresponding accompanying motions. When moving, the forearm rod and the main rod do not move. The effect of the forearm rod 10 is the same as that of the connecting rod 11, which is used to adjust the range of motion, and the main rod 9 is used to adjust the overall angle. The first movement rod is directly driven by the movement platform, or the second movement rod is driven, or the third movement rod and the second movement rod are driven together, depending on the movement track; the same second movement rod is directly driven by the lower platform, Or driven by the third movement rod; the third movement rod is driven by the movement platform. The main rod and the first movement rod are connected by bearings. Specifically, during the training process, the pneumatic muscle provides the corresponding movement force, and other parts are all doing echoing movements to achieve the predetermined trajectory. In addition, the connecting rod 11 at the upper end of the pneumatic muscle is fixed, and the connecting rod 11 The function of the is only used to adjust the range of motion, and it is fixed when the pneumatic muscle is in motion. When it is necessary to adjust the range of motion, loosen the screw of the connecting rod, adjust the connecting rod to the corresponding position and then lock it.
[0053] The robot of the present invention uses pneumatic muscles as the driver to change the traditional rigid drive and improve the compliance of the robot, so that the compliance changes can be produced in time according to the state of the patient during human-computer interaction, and the safety and comfort of the patient can be guaranteed to the greatest extent in the rehabilitation training environment . Moreover, on the basis of the above robot, by setting the corresponding control method, the patient can have both passive training and active training during the training process, and can switch between passive training and active training according to the patient's intention. It can meet the training needs of patients in different rehabilitation stages.
[0054] In this regard, the present invention discloses a parallel ankle-joint robot based on the above-mentioned pneumatic muscle as the driver, specifically an active and passive intelligent control method based on the above-mentioned parallel ankle-joint robot with the pneumatic muscle as the driver, including the following steps:
[0055] Step 1, the trajectory planning of the initial robot. In order to facilitate the transformation of the trajectory function and ensure the continuity of its position/velocity/acceleration, the sine function is used as the initial trajectory of the rehabilitation robot as an example. This method is also applicable to other composite sine-cosine function trajectories. Taking the initial trajectory along the x-axis as an example, the following formula is used to plan the initial trajectory of the robot:
[0056] x init (t)=A x sin(2πft).
[0057] Step 2, detecting the actual interaction force/torque between the patient's ankle and the robot, and comparing the actual interaction force/torque with the preset interaction force/torque threshold. Using the six-axis force/torque sensor installed between the robot's motion platform and the foot plate, continuously detect the interaction force/torque between the patient's ankle and the robot during training, and compare the interaction force/torque with the preset interaction Compared with the force/torque threshold, it is used as the judgment condition for correcting the robot motion mode.
[0058] Step 3, if the actual interaction force/torque is less than the preset interaction force/torque threshold, enter the passive training mode, maintain the current trajectory, and drive the patient to perform passive training.
[0059] Step 4. If the actual interaction force/torque is greater than the preset threshold, enter the active correction training mode to correct the current trajectory and direction of movement, while keeping the current movement speed and acceleration of the robot unchanged, ensuring the continuity of the movement of the robot and realizing the patient’s active correction training.
[0060] In the active correction training mode, there are two situations. One is to actively correct the training mode - coaxial; the other is to actively correct the training mode - different axis.
[0061] Active correction training mode-coaxial, that is, the actual interaction force/torque is coaxial with the current trajectory. At this time, the axis of the current trajectory is maintained, and the current velocity/acceleration of the robot is kept unchanged to ensure its continuity. Correction The current trajectory and direction of movement can realize active correction training for patients.
[0062] at the moment t1 Patient active interaction force/moment (F int /τ int ) greater than the preset interaction threshold F 0 /τ 0 , if the interaction force/torque is coaxial with the current trajectory, change the direction of the current trajectory according to the patient's intention, and at the same time ensure the continuity of its motion velocity/acceleration, which is achieved by correcting the phase of the trajectory function:
[0063] x adap (t)=x init (t+φ xadap )=A x sin(2πf(t+φ xadap ))
[0064] in φ x a d a p = 1 2 f - arcsin ( | x 1 | π f ) , i f x 1 0 , x ′ 1 0 , F x - F 0 orτ x - τ 0 - 1 2 f + arcsin ( | x 1 | π f ) , i f x 1 0 , x ′ 1 0 , F x F 0 orτ x τ 0 1 2 f - arcsin ( | x 1 | π f ) , i f x 1 0 , x ′ 1 0 , F x F 0 orτ x τ 0 - 1 2 f + arcsin ( | x 1 | π f ) , i f x 1 0 , x ′ 1 0 , F x - F 0 orτ x - τ 0
[0065] where x 1 is the position before trajectory correction, x 1 ' is the velocity before trajectory correction, φ xadap is the phase correction amount.
[0066] Actively correct the training mode - different axis, that is, the interaction force/torque is not on the same axis as the current motion trajectory, then change the axis of the current motion trajectory, so that the current axis motion trajectory is transformed into another axis motion trajectory, specifically as follows: Reverse the current axial motion to the zero point of the motion track to stop, and then transfer to another axial track motion at the zero point position to complete the transformation and correction of the motion track axis. Here, take the x-axis trajectory turning to the y-axis as an example:
[0067] x a d a p ( t ) = A x sin ( 2 π f ( t + φ x a d a p ) ) , w h e n | F y | F 0 o r | τ y | τ 0 , t = t 1 0 , u n t i l z e r o - c r o s sin g , t = t 2
[0068] Change the x-axis trajectory by the above formula and at t 2 Move to the zero point at all times, and then re-plan the y-axis trajectory at the zero point by the following formula:
[0069] the y adap (t)=A y sin(2πf(t yadap +φ yadap )), when x adap (t)=0
[0070] where t yadap =t-t 3 , φ y a d a p = 0 i f F y F 0 orτ y τ 0 1 2 f i f F y - F 0 orτ y - τ 0
[0071] In the above formula, in order to ensure the continuity of its movement time and trajectory, its time and phase values ​​have been corrected.
[0072] Step 5, according to the above-mentioned motion trajectory, perform closed-loop motion control on the pneumatic muscles of the robot, so as to realize precise tracking of the motion trajectory. After a new trajectory is planned according to the patient's intention, the precise and stable tracking of the trajectory is realized according to the control method. In the subsequent process, if the patient does not actively apply force to generate a large enough interaction force/moment, the robot will drive the patient to perform passive exercise training; if the patient actively applies force/torque, the trajectory function will be replanned according to the above steps to achieve passive The intelligent control of the robot that connects the mode and the active correction mode.
[0073] In addition, the motion control of the pneumatic muscles of the robot also specifically includes the following steps:
[0074] Step 5.1 Expected trajectory planning, determine the correction form of the robot, and complete the expected trajectory planning. Determine the direction of movement and expected displacement of the robot based on the needs of ankle rehabilitation training, calculate the position coordinates of the expected movement and perform online trajectory planning. Here, the sine-cosine function is used to fit the motion curve to plan the trajectory. The desired trajectories are dorsiflexion/plantarflexion directional trajectory, varus/valgus directional trajectory and adduction/abduction directional trajectory.
[0075] Step 5.2, according to the expected trajectory, the expected length of the aerodynamic muscle is calculated by kinematics inverse solution. The following will be described with specific examples. as attached Figure 7 As shown, the connection points defining the moving platform and the fixed platform are respectively m p i and f the s i , f O is the center position vector on the fixed platform, f R m is the rotation matrix of the motion platform relative to the original coordinate system, and the position vector of the motion platform can be calculated by this matrix and the information of the fixed platform, as follows:
[0076] f P i = f R m · m P i
[0077] R f m = cosθ z cosθ y A 12 A 31 sinθ z cosθ y A 22 A 23 - sinθ y cosθ y sinθ x cosθ y cosθ x
[0078] A 12 =-sinθ z cosθ x +cosθ z sinθ y sinθ x
[0079] A 22 =cosθ z cosθ x +sinθ z sinθ y sinθ x
[0080] A 31 =-cosθ z sinθ x +sinθ z sinθ y cosθ x
[0081] A 23 = sinθ z sinθ x +cosθ z sinθ y cosθ x
[0082] f L i = f O+ f R m · m P i - f S i
[0083] position vector f L i It is the length vector of the pneumatic muscle, and its length value can be calculated by the following formula:
[0084] l f i = ( L f i ) T · L f i
[0085] Step 5.3, establish the pneumatic muscle control model, using the formula F(p,k)=(p+a) e b·k +c·p·k+d·p+e establishes a function model, where F is the static tension generated by the pneumatic muscle, P is the internal air pressure of the pneumatic muscle, and parameters such as k, a, b, c, d, e are passed Coefficients obtained experimentally for the relationship between air pressure, length, and tension in pneumatic muscles.
[0086] The contraction force of a pneumatic muscle depends on the contraction rate and the internal air pressure. Based on this, the empirical data is obtained through experiments, and the static model is established under two different situations of inflation and deflation.
[0087]Step 5.4, according to the control model of the pneumatic muscle, calculate the air pressure value required for the desired length of the pneumatic muscle, and inflate/deflate the pneumatic muscle to generate a corresponding air pressure value in the pneumatic muscle. This is generally realized by air valve control, and the air pressure control proportional valve is configured to inflate/deflate the pneumatic muscles, so that the corresponding air pressure values ​​are generated in the pneumatic muscles.
[0088] In step 5.5, the actual motion trajectory of the robot is obtained, and the actual length of the pneumatic muscle is calculated by kinematics inverse solution. In general, the actual trajectory of the robot is acquired by the angle sensor installed on the robot, and the actual length of the pneumatic muscle is calculated by using the kinematics inverse solution method according to the actual trajectory.
[0089] Step 5.6, perform closed-loop control on the pneumatic muscle, specifically compare the obtained actual length of the pneumatic muscle with the expected length of the pneumatic muscle, correct the air pressure value of the pneumatic muscle according to the comparison error, control the length of the pneumatic muscle and then control the robot to track the desired trajectory. In this case, the robot's dynamic platform can track the predetermined ankle joint motion trajectory to the maximum extent. Here, the advanced PID control method is used to realize the closed-loop control of the pneumatic muscle to ensure the accuracy and stability of the robot movement.
[0090] Through the above control method, the active and passive training modes of the ankle robot can be switched seamlessly and freely. When the patient does not want active training, the robot drives the affected limb to perform passive movement. When the patient wants active training, the trajectory motion state is corrected through its interaction force/torque, reflecting its active control ability to the robot, which can greatly improve the patient's ability to train. levels of active engagement and recovery in
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