Knee joint exoskeleton adopting double four-bar mechanisms

Abstract

The invention belongs to the field of wearable exoskeletons, and particularly relates to a knee joint exoskeleton adopting double four-bar mechanisms. Comprising a thigh mechanism, a shank mechanism and a transmission mechanism, the thigh mechanism comprises a thigh rod, the shank mechanism comprises a shank rod, and the transmission mechanism comprises a power transmission mechanism and a thigh and shank connection transmission mechanism; the power transmission mechanism is a four-connecting-rod mechanism and comprises a motor, a small gear and a large gear which are mounted on the thigh rod, and a transmission connecting rod of which one end is connected with the large gear through a fisheye bearing and the other end is connected with the shank rod through a fisheye bearing; and the thigh and shank connection transmission mechanism is a four-bar mechanism for realizing the instant center of knee joint movement. The knee joint is driven to move upwards, the overall rotational inertia of the mechanism is greatly reduced, the power assisting capacity is improved, double four-bar linkage synchronous transmission is adopted, the instantaneous center of movement of the knee joint of the human body is better fitted, and the movement comfort of the human body is improved.

Description

Technical Field

[0001] This invention relates to the field of wearable exoskeletons, and more specifically to a knee exoskeleton employing a double four-bar linkage mechanism. Background Technology

[0002] This section provides only background information relevant to this disclosure and is not necessarily prior art.

[0003] Assisted exoskeletons are widely used in military, industrial, and rehabilitation fields. As modern wearable equipment, they are primarily used to enhance human mobility while providing protection for the wearer. With social progress and the accelerating aging population, human exoskeletons have developed rapidly.

[0004] Meanwhile, the bearing connection widely used in wearable exoskeletons for the knee joint is difficult to match the instantaneous center of motion of the human knee joint, which can easily cause discomfort. In the utility model patent with patent number CN215132743U, a multi-axis knee joint exoskeleton structure is disclosed. This mechanism discloses a four-bar linkage that converts linear transmission into rotation. However, it is difficult to control the rotation through linear motion, making it difficult to achieve real-time control of the mechanism. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a knee exoskeleton employing a double four-bar linkage mechanism, which solves the problems of large inertial torque of the knee joint drive device relative to the hip joint and mismatch between knee joint movement and the human body in existing exoskeletons.

[0006] A knee exoskeleton employing a double four-bar linkage mechanism is characterized by comprising a thigh mechanism, a lower leg mechanism, and a transmission mechanism, wherein the thigh mechanism is connected to the lower leg mechanism via the transmission mechanism; the thigh mechanism is equipped with a drive device, which drives the lower leg mechanism to move via the transmission mechanism. The drive device is a motor.

[0007] The transmission mechanism includes a large gear, a transmission connecting rod, a knee joint connecting long rod, and a knee joint connecting short rod. The large gear is rotatably mounted on the thigh mechanism. The two ends of the transmission connecting rod are rotatably connected to the large gear and the lower leg mechanism respectively, forming a crank-rocker mechanism. The two ends of the knee joint connecting long rod and the knee joint connecting short rod are rotatably connected to the thigh mechanism and the lower leg mechanism respectively, forming a double-crank mechanism. The output end of the drive device is connected to the large gear. The two mechanisms work together: the first four-bar linkage drives the lower leg mechanism to produce basic flexion and extension movements, while the second four-bar linkage forces the relative motion of the thigh mechanism and the lower leg mechanism to simulate the trajectory of the physiological instantaneous center of gravity of the human knee joint.

[0008] Furthermore, the thigh leg bar has two parallel inclined thigh leg bar grooves, which are located on one side of the front of the human body; the lower leg leg bar has two parallel inclined lower leg leg bar grooves, and the knee joint connecting rod is located on one side of the front of the human body. When the thigh leg bar and the lower leg leg bar are parallel, the extension lines of the two sets of grooves are mirror symmetrical about the central axis of the two leg bars.

[0009] The two ends of the knee joint connecting rod and the knee joint connecting rod are fixedly connected by fisheye bearings and screws set in two sets of opposite sliding grooves. The connection positions of the two ends of the knee joint connecting rod and the knee joint connecting rod can be adjusted through the two sets of sliding grooves. The positions of the knee joint connecting rod and the knee joint connecting rod within the sliding grooves are adjustable, and the corresponding positions are fixed by screws and nuts. The fisheye bearings and screws at both ends of the knee joint connecting rod and the knee joint connecting rod are interference-fitted. Before using the device, adjust the positions of the knee joint connecting rod and the knee joint connecting rod to adapt to users of different body types and walking habits.

[0010] Furthermore, the lengths of the transmission connecting rod, the long knee joint connecting rod, and the short knee joint connecting rod are all adjustable, and the main body is an adjustable threaded rod. Before using the device, the lengths of the transmission connecting rod, the long knee joint connecting rod, and the short knee joint connecting rod can be adjusted to suit users of different body sizes.

[0011] Furthermore, the thigh mechanism includes a thigh telescopic rod and a thigh length adjusting lever. The thigh telescopic rod is adjustable in length, and the thigh length adjusting lever locks the thigh telescopic rod at the desired length position. This allows the thigh mechanism to be length-adjustable.

[0012] Furthermore, the calf mechanism includes a calf telescopic rod and a calf length adjusting lever. The length of the calf telescopic rod is adjustable, and the calf length adjusting lever locks the calf telescopic rod at the desired length position. This allows the calf mechanism to be length-adjustable.

[0013] Furthermore, the lower leg bar has a long U-shaped groove at the top, and the upper part of the thigh leg bar has an extension plate that extends into the upper part of the U-shaped groove and does not contact the side wall of the U-shaped groove, so that the lower leg bar and the thigh leg bar can move in the same plane.

[0014] Furthermore, the thigh mechanism is equipped with a first gyroscope; the lower leg mechanism is equipped with a second gyroscope. These are used to monitor joint movement.

[0015] Furthermore, the thigh mechanism is equipped with thigh straps; the calf mechanism is equipped with calf straps. This facilitates user comfort and ease of wear.

[0016] Furthermore, the feature is that inertial measurement units are respectively provided on the thigh leg rod and the lower leg mechanism. The obtained data assists the user in constructing a mathematical model of the lower limb exoskeleton robot and adjusting the device.

[0017] Compared with the prior art, the significant advantages of this invention are:

[0018] The exoskeleton of this invention comprises four components: a transmission gear, a transmission connecting rod, a thigh rod, and a calf rod, forming the first four-bar linkage required for transmission. This enables the drive motor, located at the thigh, to drive the calf. The second four-bar linkage, connecting the knee joint long rod and the knee joint short rod, connects the thigh and calf mechanisms, forming the second four-bar linkage for transmission. The long rod is located on the front of the thigh, and the short rod is located on the back of the thigh. During the rotation of the calf relative to the thigh, the instantaneous center of motion of the four-bar linkage is used to match the rotation of the human knee joint. Thus, the two four-bar linkages achieve transmission by matching the instantaneous center of motion of the human knee joint.

[0019] The transmission connecting rod, the knee joint connecting long rod, and the knee joint connecting short rod described in this invention all adopt the connection method of fisheye bearing and threaded rod. The length can be adjusted by rotating the threaded connecting rod to adapt to different human body requirements. In order to better fit the instantaneous center of motion of the human body, the thigh leg rod and the calf leg rod are provided with sliding grooves. After adjusting the length of the transmission connecting rod, the knee joint connecting long rod, and the knee joint connecting short rod, the position of the fisheye bearing in the sliding groove can be adjusted to adjust the instantaneous center of motion of the knee joint. Attached Figure Description

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0021] Figure 1 This is a schematic diagram of the exoskeleton of the present invention in an upright state.

[0022] Figure 2 This is a schematic diagram of the bending state of the exoskeleton of the present invention.

[0023] Figure 3 This is a schematic diagram of the thigh mechanism of the present invention.

[0024] Figure 4 This is a schematic diagram of the transmission mechanism of the present invention in a bent state.

[0025] Figure 5 This is a schematic diagram of the transmission mechanism of the present invention in an upright state.

[0026] Figure 6 This is a schematic diagram of the lower leg mechanism of the present invention.

[0027] Figure 7 This is a flowchart of the control method of the present invention.

[0028] Explanation of reference numerals in the attached drawings: 1-Thigh mechanism, 2-Transmission mechanism, 3-Lower leg mechanism, 101-Thigh strap, 102-Thigh gear housing, 103-Short rod with threaded hole in thigh, 104-Thigh telescopic rod, 105-Thigh connecting device, 106-Thigh length adjusting pressure rod, 107-Motor, 108-First gyroscope cover plate, 109-First gyroscope, 110-Thigh leg rod, 111-Thigh leg rod slide groove, 201-Small gear, 202-Large gear, 203-Transmission connecting rod, 204-Knee joint connecting long rod, 205-Knee joint connecting short rod, 301-Lower leg strap, 302-Lower leg rod, 303-Second gyroscope, 304-Second gyroscope cover plate, 305-Short rod with threaded hole in lower leg, 306-Lower leg length adjusting pressure rod, 307-Lower leg telescopic rod, 308-Lower leg rod slide groove. Detailed Implementation

[0029] like Figure 1-6 As shown, a knee exoskeleton employing a double four-bar linkage mechanism includes a thigh mechanism 1, a transmission mechanism 2, and a lower leg mechanism 3; the thigh mechanism 1 and the lower leg mechanism 2 are connected through the transmission mechanism 3.

[0030] The thigh drive motor 107 is connected to the pinion 201, which is connected to the large gear 202. One end of the transmission connecting rod 203 is mounted on the large gear 202 with a fisheye bearing, and the other end is mounted on the lower leg rod 302 with a fisheye bearing. These four components—the gear mechanism consisting of the large and small gears 201 and 202, the transmission connecting rod 203, the thigh leg rod 110, and the lower leg rod 302—form the first four-bar linkage required for transmission. The knee joint connecting long rod 204 and the knee joint connecting short rod 205 are connected at one end with a fisheye bearing and at the other end with a fisheye bearing. The lower leg mechanism 2 is connected to form the second four-bar linkage in the transmission process; the thigh drive motor 107 drives the transmission pinion 201, which in turn drives the transmission gear 202. The transmission gear 202 drives the rotation of the lower leg rod 302 through the transmission connecting rod 203. During the rotation of the lower leg rod 302, the knee joint connecting long rod 204 and knee joint connecting short rod 205 are connected to the thigh mechanism 1 and the lower leg mechanism 2 to form the second four-bar linkage in the transmission process. The transmission process is achieved by fitting the instantaneous center of motion of the human knee joint through the two four-bar linkages.

[0031] The first four-bar linkage receives power from the motor, amplifies the torque, and converts the motion mode to drive the lower leg mechanism to produce basic flexion and extension movements.

[0032] The second four-bar linkage forces the relative motion of the thigh and lower leg mechanisms to simulate the trajectory of the physiological instantaneous center of gravity of the human knee joint. This corrects the simple circular trajectory that might be produced when the first mechanism acts alone, making it more consistent with the complex biomechanical characteristics of the human body.

[0033] Combination Figure 3 The thigh mechanism 1 sequentially includes a thigh strap 101, a thigh gear housing 102, a thigh threaded short rod 103, a thigh telescopic rod 104, a thigh connecting device 105, a thigh length adjusting pressure rod 106, a thigh drive motor 107, a gyroscope cover plate 108, a gyroscope 109, and a thigh leg rod 110. The thigh gear housing 102 is connected to the thigh leg rod 110 via a threaded hole. The thigh drive motor 107 is connected to the thigh gear housing 102 via bolts. The thigh strap 101 is bolted to the inside of the thigh leg rod 110. The thigh telescopic rod 104 loses the force pressing the thigh leg rod and the telescopic rod after the thigh length adjusting pressure rod 106 is released, allowing it to be pulled out to achieve length adjustment. There are two parallel thigh leg rod grooves 111 at a certain angle to the lower edge of the thigh leg rod below the thigh leg rod 110. The thigh threaded short rod 103 and the thigh length adjusting pressure rod 106 cooperate to control and fix the extension and retraction of the thigh telescopic rod 104.

[0034] Combination Figure 4 , Figure 5 The thigh drive motor 107 is connected to the transmission pinion 201, which is connected to the transmission gear 202. The thigh drive motor 107 is connected to the transmission pinion 201, which is connected to the transmission gear 202. One end of the transmission connecting rod 203 is mounted on the transmission gear 202 with a fisheye bearing, and the other end is mounted on the lower leg rod 302 with a fisheye bearing. The gear mechanism consisting of the transmission pinions 201 and 202, the transmission connecting rod 203, the thigh leg rod 110, and the lower leg rod 302 constitute the first four-bar linkage required for transmission. The knee joint connecting long rod 304 and the knee joint connecting short rod 305 are both supported by fisheye bearings at one end. The thigh-connecting mechanism 1 and the lower leg-connecting mechanism 2 connected by the fisheye bearing at the other end form the second four-bar linkage in the transmission process. The transmission connecting rod 202, the knee joint connecting long rod 204, and the knee joint connecting short rod 205 include fisheye bearings and threaded connecting rods. The length of the rods can be adjusted by rotating the threaded connecting rods to accommodate different heights. The fisheye bearings are fixed in the grooves of the thigh and lower leg rods 110 and 302 by bolts. Based on changing the length of the transmission connecting rod 203, the knee joint connecting long rod 204, and the knee joint connecting short rod 205 by rotating the threaded pair of the transmission connecting rod, the knee joint connecting long rod, and the knee joint connecting short rod, the instantaneous center of motion of the knee joint of different human bodies can be adjusted by moving the rods in the grooves.

[0035] Combination Figure 6The lower leg mechanism 3 sequentially includes a lower leg strap 301, a lower leg rod 302, a gyroscope 303, a gyroscope cover plate 304, a lower leg threaded hole short rod 305, a lower leg length adjusting pressure rod 306, and a lower leg telescopic rod 307. The lower leg strap 302 is bolted inside the lower leg rod. The lower leg rod 302 is bolted to the fisheye bearing below the transmission connecting rod 203. The gyroscope 303 is mounted on the lower leg rod, with the gyroscope cover plate 304 mounted on top, and is threaded to the lower leg rod 302 via bolts. Below the lower leg rod 302 are two parallel sliding grooves, lower leg rod grooves 308, forming a certain angle with the lower edge of the lower leg rod 302; and their direction is opposite to that of the sliding grooves on the thigh leg rod 110. The lower leg threaded hole short rod 305 and the lower leg length adjusting pressure rod 306 cooperate to control the extension and retraction of the lower leg telescopic rod 307.

[0036] Combination Figure 7 An exoskeleton with a double four-bar linkage for the knee joint and its control method are described below:

[0037] Step 1: Using the inertial measurement unit at the connection point above the thigh leg bar as a fixed reference point, construct a mathematical model of the lower limb exoskeleton robot. By changing the relative position, the position of the inertial measurement unit installed below the lower leg bar relative to the reference point can be calculated. The posture change of the lower leg bar from the reference point after adjusting the distance can be obtained, thereby obtaining the motion information of the human joint and solving the relative position of the knee joint link.

[0038] Step 2: After the wearer puts on the lower limb exoskeleton robot, keep it still for a certain period of time to collect initial information from the knee joint encoder and each inertial measurement unit.

[0039] Step 3: When the wearer exercises, the configured inertial measurement unit collects the wearer's lower limb motion data and transmits the data to the microprocessor. Through data processing, the human joint motion information is obtained, and the corresponding exoskeleton joint drive mechanism is controlled to output, realizing the movement of the lower limb exoskeleton. The exoskeleton movement will drive the joint encoder to start recording, which can measure the kinematic information of the exoskeleton joint in real time, monitor whether the movement of the lower limb exoskeleton mechanism is correct, and use it as feedback input to the processor to complete the closed-loop control of the joint drive mechanism.

[0040] This invention provides a concept and method for a knee exoskeleton employing a double four-bar linkage mechanism. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A knee joint exoskeleton employing a double four-bar linkage mechanism, characterized in that, It includes a thigh mechanism (1), a calf mechanism (3) and a transmission mechanism (2). The thigh mechanism (1) is connected to the calf mechanism (3) through the transmission mechanism (2). The thigh mechanism (1) is provided with a driving device, which drives the calf mechanism (3) to move through the transmission mechanism (2). The transmission mechanism (2) includes a large gear (202), a transmission connecting rod (203), a knee joint connecting long rod (204), and a knee joint connecting short rod (205). The large gear (202) is rotatably mounted on the thigh mechanism (1). The two ends of the transmission connecting rod (203) are rotatably connected to the large gear (202) and the calf mechanism (3) respectively to form a crank rocker mechanism. The two ends of the knee joint connecting long rod (204) and the knee joint connecting short rod (205) are rotatably connected to the thigh mechanism (1) and the calf mechanism (3) respectively to form a double crank mechanism. The output end of the drive device is connected to the large gear (202).

2. The knee exoskeleton with a double four-bar linkage mechanism according to claim 1, characterized in that, The thigh leg bar (110) is provided with two parallel inclined thigh leg bar grooves (111); the lower leg bar (302) is provided with two parallel inclined lower leg bar grooves (308). When the thigh leg bar (110) and the lower leg bar (302) are parallel, the extension lines of the two sets of grooves are mirror symmetrical about the central axis of the two leg bars. The two ends of the knee joint connecting long rod (204) and the knee joint connecting short rod (205) are fixedly connected by a fisheye bearing and a screw set in two sets of upper and lower opposite sliding grooves, respectively. The connection positions of the two ends of the knee joint connecting long rod (204) and the knee joint connecting short rod (205) can be adjusted by the two sets of sliding grooves.

3. The knee joint exoskeleton with a double four-bar linkage mechanism according to claim 2, characterized in that, The lengths of the transmission connecting rod (203), the knee joint connecting long rod (204), and the knee joint connecting short rod (205) are all adjustable.

4. The knee exoskeleton with a double four-bar linkage mechanism according to claim 1, characterized in that, The thigh mechanism (1) includes a thigh telescopic rod (104) and a thigh length adjusting pressure rod (106). The length of the thigh telescopic rod (104) is adjustable, and the thigh length adjusting pressure rod (106) locks the thigh telescopic rod (104) at the desired length position.

5. The knee exoskeleton with a double four-bar linkage mechanism according to claim 1, characterized in that, The lower leg mechanism (3) includes a lower leg telescopic rod (307) and a lower leg length adjusting pressure rod (306). The length of the lower leg telescopic rod (307) is adjustable, and the lower leg length adjusting pressure rod (306) locks the lower leg telescopic rod (307) at the desired length position.

6. The knee exoskeleton with a double four-bar linkage mechanism according to claim 1, characterized in that, The lower leg rod (302) has a long U-shaped groove at the top, and the upper part of the thigh leg rod (110) has an extension plate that extends into the upper part of the U-shaped groove and does not contact the side wall of the U-shaped groove.

7. The knee exoskeleton with a double four-bar linkage mechanism according to claim 1, characterized in that, The driving device is a motor (107).

8. The knee exoskeleton with a double four-bar linkage mechanism according to claim 1, characterized in that, The thigh mechanism (1) is equipped with a first gyroscope (109); the lower leg mechanism (3) is equipped with a second gyroscope (303).

9. The knee exoskeleton with a double four-bar linkage mechanism according to claim 1, characterized in that, The thigh mechanism (1) is provided with a thigh strap (101); the calf mechanism (3) is provided with a calf strap (301).

10. The knee exoskeleton with a double four-bar linkage mechanism according to claim 1, characterized in that, Inertial measurement units are respectively provided on the thigh leg rod (1) and the lower leg mechanism (3).

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