PASSIVE LOWER LIMB POWER-ASSISTED EXOSKELETON BASED ON
GRAVITATIONAL POTENTIAL ENERGY LOCKING
TECHNICAL FIELD
[0001] The present disclosure relates to the technical field of power-assisting devices, and in particular relates to a passive lower limb power-assisted exoskeleton based on gravitational potential energy locking.
BACKGROUND
[0002] The existing passive lower limb exoskeleton design mostly makes use of the swing energy generated during walking, which is the source of energy converted into the power assistance, but the energy capable of being used is less and is hard to play a role in power-assisting. In addition, most passive lower limb exoskeletons use the springs for energy storage, but most in the form of immediate release for power assistance, while the walking gaits of the human are divided into different phases, such immediate feedback is difficult to produce a good power-assisting effect on the swing phase, i.e., the walking leg lifting phase, in general, the energy has been released at the terminal stance, leading to inefficient energy use and poor coupling between the exoskeleton and the human gait.
SUMMARY
[0003] Technical Problem [0004] The energy use efficiency is low, and the coupling between the exoskeleton and the human gait is poor.
[0005] Technical Solution [0006] A passive lower limb power-assisted exoskeleton based on gravitational potential energy locking, includes two power-assisting connecting rod mechanisms. The power-assisting connecting rod mechanisms each include a waist rod member, a thigh rod member and a shank rod member; an upper end and a lower end of the thigh rod member are connected to a lower end of the waist rod member and an upper end of the shank rod member respectively in a hinged manner. A small sprocket, a rotatable pawl and a swingable position adjusting column body are mounted on the waist rod member; a ratchet wheel and the small sprocket are of an integrated structure to achieve synchronous rotation; an end of the position adjusting column body abuts against an end of the pawl; the small sprocket and a large sprocket are connected by means of a chain; a rotating disc is fixed to the thigh rod member, a first cylinder and a second cylinder are fixed to a side surface of the rotating disc. A foot rod member and a sliding hole rod member are mounted at a lower end of the shank rod member in a hinged manner; a bolt is mounted at an end of the foot rod member, and the bolt is capable of freely sliding in a strip-shaped hole in an end of the sliding hole rod member; a lower end of a first spring is fixed to the thigh rod member, and an upper end of the first spring is connected to an end of a steel wire rope. A first fixed pulley is mounted on the thigh rod member, and an other end of the steel wire rope is connected to the end of the sliding hole rod member after bypassing the first fixed pulley; the upper end of the first spring is connected to an end of a crank connecting rod, and an other end of the crank connecting rod is connected to the large sprocket to achieve synchronous rotation; when a foot touches on ground. The sliding hole rod member is capable of rotating accordingly to make contact with the ground; and when the rotating disc rotates bidirectionally along with the thigh rod member, the first cylinder and the second cylinder are configured to toggle the position adjusting column body so as to control the pawl to be engaged with, or disengaged from, the ratch wheel.
[0007] Further, a positioning plate is mounted on an outer surface of the waist rod member, a through hole is provided in the positioning plate, the position adjusting column body is inserted into the through hole, and a diameter of the through hole is greater than that of the position adjusting column body; a shaft shoulder is arranged at a lower end of the position adjusting column body, a nut is mounted in a middle of the position adjusting column body, a second spring is sleeved on the position adjusting column body, a lower end of the second spring abuts against the positioning plate, and an upper end of the second spring abuts against the nut.
[0008] Further, an end of the pawl is provided with an arc-shaped groove, an upper end of the position adjusting column body is inserted into the arc-shaped groove, a middle of the pawl is rotatably sleeved on a mounting column, and the mounting column is vertically fixed to the outer surface of the waist rod member.
[0009] Further, the crank connecting rod is formed by hinging two rods.
[0010] Further, a spring guide sleeve is mounted on the thigh rod member, the first spring is arranged in the spiing guide sleeve, the spring guide sleeve is in a shape of a square tube and has a tube length along the thigh rod member; an outer tube wall of the spring guide sleeve is provided with a strip-shaped opening along a tube length direction, and two ends of the strip-shaped opening extend to two end of the spring guide sleeve; and the end of the crank connecting rod is lapped to the outer tube wall of the spring guide sleeve.
[0011] Further, a second fixed pulley is mounted on a hinge shaft at a hinge position where the thigh rod member and the shank rod member are hinged; the second fixed pulley is located below the spring guide sleeve, the first fixed pulley is located above the spring guide sleeve, and the steel wire rope extending from the upper end of the first spring bypasses upwards the first fixed pulley, extends downwards, and then is fixed to the end of the sliding hole rod member after winding around the second fixed pulley for one circle.
[0012] Further, a hinge point where the foot rod member and the shank rod member are hinged is located above a hinge point where the sliding hole rod member and the shank rod member are hinged.
[0013] The passive lower limb power-assisted exoskeleton based on gravitational potential energy locking further includes a waist fixing sleeve, two thigh fixing sleeves, two shank fixing sleeves, and two foot fixing sleeves. The two foot fixing sleeves are connected to lower ends of the two shank fixing sleeves respectively, an upper end of the waist rod member is fixed to a side of the waist fixing sleeve, a middle of the thigh rod member is fixed to an outer side of one of the thigh fixing sleeves, and a middle of the shank rod member is fixed to an outer side of one of the shank fixing sleeves. The two power-assisting connecting rod mechanisms are distributed at two sides of the waist fixing sleeve; the waist fixing sleeve, the thigh fixing sleeves and the shank fixing sleeves each arc in a shape of sleeve, and a front side of each sleeve is opened or closed by means of a fastening belt, and the foot fixing sleeves each arc in a shape of shoe to support the foot.
[0014] Beneficial Technical Effects [0015] The present disclosure provides the passive lower limb power-assisted exoskeleton based on gravitational potential energy locking to solve the problems of less utilized energy and poor coupling between the exoskeleton and the human gait in the background. A user can wear the lower limb power-assisted exoskeleton by means of the waist fixing sleeve, two thigh fixing sleeves, two shank fixing sleeves and two foot fixing sleeves, and then can walk in normal gaits after wearing the lower limb power-assisted exoskeleton. When the walking gait is at the terminal swing, the foot starts to be positioned on the ground, the left end of the sliding hole rod member starts to make contact with the ground, and under the action of the ground reaction force, the sliding hole rod member rotates clockwise to pull the traction steel wire rope, and the first spring is gradually stretched along the spring guide sleeve under the action of the traction steel wire rope for energy storge. At the moment, an angle between the thigh rod member and the waist rod member is gradually increased, the rotating disc rotates clockwise, the second cylinder on the rotating disc also rotates clockwise, and the position adjusting column body is enabled, by the first cylinder on the rotating disc, to rotate clockwise, such that the pawl is enabled to rotate counterclockwise around a connecting point, to be engaged with the ratchet wheel, and the crank connecting rod is located at the uppermost extreme position for locking and energy storage. When the walking gait is in the period from the terminal stance to the initial swing, the ratchet wheel and the pawl are in an engaged state, the chain transmission does not affect the engagement, and the lower end of the crank connecting rod begins to move linearly with respect to the thigh rod member under the pulling force of the first spring. In this process, the crank connecting rod rotates counterclockwise around its upper end point, the force applied to the side surface of the spring guide sleeve by the common action of the crank connecting rod and the first spring is used for power-assisting the leg lifting process. When the process of power assistance by energy release is finished, the hip joint reaches the maximum movement angle, the rotating disc, which moves with the thigh rod member, enables the pawl to be disengaged from the ratchet wheel through the position adjusting column body under the action of the pushing force of the first cylinder on the rotating disc behind, and at the moment, the first spring is at its original length.
[0016] At the stance phase during walking, the exoskeleton is configured for energy storage and performing locking, and the first spring is kept at a stretched state. At the initial swing, the user starts to perform the leg lifting phase, such that the energy is released, the exoskeleton is unlocked, and the first spring is recovered to the original length to help user to continue the leg swing action and to perform power assisting. After entering the next cycle, the foot of the user touches on the ground to enter the stance phase, thus performing cycle circulation.
[0017] In the whole phase, the gravitational potential energy during walking can be effectively used for power-assisting a user, and meanwhile, by means of a locking mechanism, the energy can be released during leg lifting, i.e., the swing phase, after being stored at the walking stance phase, which improves the coupling between an exoskeleton and human body movement.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic structural diagram of the present disclosure.
[0019] FIG. 2 is a schematic structural diagram of the present disclosure from another angle. [0020] FIG. 3 is a schematic diagram of a partial structure of FIG. 1.
[0021] FIG. 4 is a schematic diagram of a partial structure of FIG. 3.
[0022] FIG. 5 is a schematic diagram showing FIG. 4 with a waist rod member removed.
[0023] FIG. 6 is a schematic diagram showing a spring guide sleeve mounted.
[0024] Reference numerals: 1-waist fixing sleeve; 2-thigh fixing sleeve; 3-shank fixing sleeve; 4-foot fixing sleeve; 5-waist rod member; 6-thigh rod member; 7-shank rod member; 8-small sprocket; 9-chain; 10-rotating disc; 11-first fixed pulley; 12-second fixed pulley; 13-pawl; 14-crank connecting rod; 15-steel wire rope; 16-foot rod member; 17-sliding hole rod member; 18-ratchet wheel; 19-positioning plate; 20-position adjusting column body; 21-nut; 22-second spring; 23-large sprocket; 24-first spring; 25-spring guide sleeve; 26-first cylinder; 27-second cylinder; 28-fastening belt.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] The specific embodiments of the present disclosure are described below with reference to the accompanying drawings.
[0026] As shown in FIG. 1 to FIG. 6, a passive lower limb power-assisted exoskeleton based on gravitational potential energy locking of the embodiment includes two power-assisting connecting rod mechanisms. The power-assisting connecting rod mechanisms each includes a waist rod member 5, a thigh rod member 6 and a shank rod member 7. An upper end and a lower end of the thigh rod member 6 are respectively connected to a lower end of the waist rod member 5 and an upper end of the shank rod member 7 in a hinged manner. A small sprocket 8, a rotatable pawl 13 and a swingable position adjusting column body 20 are mounted on the waist rod member 5. A ratchet wheel 18 and the small sprocket 8 are of an integrated structure to achieve synchronous rotation. An end of the position adjusting column body 20 abuts against an end of the pawl 13. The small sprocket 8 and a large sprocket 23 are connected by means of a chain 9. A rotating disc 10 is fixed to the thigh rod member 6, a first cylinder 26 and a second cylinder 27 are fixed to a side surface of the rotating disc 10. A foot rod member 16 and a sliding hole rod member 17 are mounted at the lower end of the shank rod member 7 in a hinged manner. A bolt is mounted at one end of the foot rod member 16, and the bolt can slide freely in a strip-shaped hole in one end of the sliding hole rod member 17. The lower end of a first spring 24 is fixed to the thigh rod member 6, and the upper end of the first spring 24 is connected to one end of a steel wire rope 15. A first fixed pulley 11 is mounted on the thigh rod member 6, and the other end of the steel wire rope 15 is connected to the one end of the sliding hole rod member 17 after bypassing the first fixed pulley 11. The upper end of the first spring 24 is connected to one end of a crank connecting rod 14, and the other end of the crank connecting rod 14 is connected to the large sprocket 23 to achieve synchronous rotation. When a foot touches on the ground, the sliding hole rod member 17 may rotate accordingly to make contact with the ground; and when the rotating disc 10 rotates bidirectionally along with the thigh rod member 6, the first cylinder 26 and the second cylinder 27 are respectively configured to toggle the position adjusting column body 20 so as to control the pawl 13 to be engaged with, or disengaged from, the ratch wheel 18.
[0027] A positioning plate 19 is mounted on an outer surface of the waist rod member 5, a through hole is provided in the positioning plate 19, the position adjusting column body 20 is inserted into the through hole, and a diameter of the through hole is greater than that of the position adjusting column body 20. A shaft shoulder is arranged at a lower end of the position adjusting column body 20, a nut 21 is mounted in a middle of the position adjusting column body 20, and a second spring 22 is sleeved on the position adjusting column body 20. A lower end of the second spring 22 abuts against the positioning plate 19, and the upper end of the second spring 22 abuts against the nut 21.
[0028] An arc-shaped groove is provided in one end of the pawl 13, an upper end of the position adjusting column body 20 is inserted into the arc-shaped groove; a middle of the pawl 13 is sleeved on a mounting column in a rotatable manner, the mounting column is vertically fixed at the outer surface of the waist rod member 5.
[0029] The crank connecting rod 14 is formed by hinging two rods.
[0030] A spring guide sleeve 25 is mounted on the thigh rod member 6, the first spring 24 is arranged in the spring guide sleeve 25, and the spring guide sleeve 25 is in a shape of a square tube and has a tube length along the thigh rod member 6. An outer tube wall of the spring guide sleeve 25 is provided with a strip-shaped opening along a tube length direction, and two ends of the strip-shaped opening extend to two ends of the spring guide sleeve 25. The end of the crank connecting rod 14 is lapped to the outer tube wall of the spring guide sleeve 25.
[0031] A second fixed pulley 12 is mounted on a hinge shall at a hinge position where the thigh rod member 6 and the shank rod member 7 are hinged. The second fixed pulley 12 is located below the spring guide sleeve 25, the first fixed pulley 11 is located above the spring guide sleeve 25, and the steel wire rope 15 extending from the upper end of the first spring 24 bypasses the first fixed pulley 11 upwards, extends downwards, and then is fixed to the end of the sliding hole rod member 17 after winding around the second fixed pulley 12 for one circle. A hinge point where the foot rod member 16 and the shank rod member 7 are hinged is located above a hinge point where the sliding hole rod member 17 and the shank rod member 7 are hinged.
[0032] The passive lower limb power-assisted exoskeleton based on gravitational potential energy locking further includes a waist fixing sleeve 1, two thigh fixing sleeves 2, two shank fixing sleeves 3, and two foot fixing sleeves 4. The two foot fixing sleeves 4 are respectively connected to lower ends of the two shank fixing sleeves 3, an upper end of the waist rod member 5 is fixed to a side of the waist fixing sleeve 1, a middle of the thigh rod member 6 is fixed to an outer side of one of the thigh fixing sleeves 2, and a middle of the shank rod member 7 is fixed to an outer side of one of the shank fixing sleeves 3. The two power-assisting connecting rod mechanisms are distributed at two sides of the waist fixing sleeve 1; the waist fixing sleeve 1, the thigh fixing sleeves 2 and the shank fixing sleeves 3 each are in a shape of sleeve, and a front side of the sleeve is opened or closed by means of a fastening belt 28, and the foot fixing sleeves 4 each are in a shape of shoe to support the foot. The user may wear the passive lower limb power-assisted exoskeleton by opening fastening belts at front ends of the waist fixing sleeve I, the thigh fixing sleeves 2 and the shank fixing sleeves 3, and then check the fixation and connection situations after the exoskeleton is fixed.
[0033] The present disclosure provides the passive lower limb power-assisted exoskeleton based on gravitational potential energy locking to solve the problems of less utilized energy and poor coupling between the exoskeleton and the human gait in the background. A user can wear the lower limb power-assisted exoskeleton by means of the waist fixing sleeve 1, two thigh fixing sleeves 2, two shank fixing sleeves 3 and two foot fixing sleeves 4, and then can walk in normal gaits after wearing the lower limb power-assisted exoskeleton. When the walking gait is at the terminal swing, the foot starts to be positioned on the ground, the left end of the sliding hole rod member 17 starts to make contact with the ground, and under the action of the ground reaction force, the sliding hole rod member 17 rotates clockwise to pull the traction steel wire rope 15, and the first spring 24 is gradually stretched along the spring guide sleeve 25 under the action of the traction steel wire rope 15 for energy storge. At the moment, an angle between the thigh rod member 6 and the waist rod member 5 is gradually increased, the rotating disc 10 rotates clockwise, and the second cylinder 27 on the rotating disc 10 also rotates clockwise, such that the pawl 13 is enabled to rotate counterclockwise around a connecting point to be engaged with the ratchet wheel 18, and the crank connecting rod 14 is located at the uppermost extreme position for locking and energy storage. When the walking gait is in the period from the terminal stance to the initial swing, the ratchet wheel 18 and the pawl 13 are in an engaged state, the chain transmission does not affect the engagement, and the lower end of the crank connecting rod 14 begins to move linearly with respect to the thigh rod member 6 under the pulling force of the first spring 24. In this process, the crank connecting rod 14 rotates counterclockwise around its upper end point, the force applied to the side surface of the spring guide sleeve 25 by the crank connecting rod 14 and the first spring 24 together is used for power-assisting the leg lifting process. When the process of power assistance by energy release is finished, the hip joint reaches the maximum movement angle, the rotating disc 10, which moves with the thigh rod member 6, enables the pawl 13 to be disengaged from the ratchet wheel 18 through the position adjusting column body 20 under the action of the pushing force of the first cylinder 26 on the rotating disc 10, and at the moment, the first sming 24 is at its original length.
[0034] At the stance phase during walking, the exoskeleton is configured for energy storage and performing locking, and the first spring 24 is kept in a stretched state. At the initial swing, the user starts to perform the leg Biting phase, such that the energy is released, the exoskeleton is unlocked, and the first spring 24 is recovered to the original length to help user to continue the leg swing action and to perform power assisting. After entering the next cycle, the foot of the user touches on the ground to enter the stance phase, thus performing cycle circulation.
[0035] One end of the steel wire rope 15 in the exoskeleton is connected to the upper end of the first spring 24 after bypassing the second fixed pulley 12 and the first fixed pulley 11. During walking, the first spring 24, under the action of the external force, is stretched for the storage of gravitational potential energy.
[0036] In the process that the human foot is in gradual contact with the ground, the sliding hole rod member 17 makes contact with the ground, the left end of the sliding hole rod member 17 moves clockwise upwards around a revolute pair, while the right end of the sliding hole rod member moves clockwise downwards to drive the traction steel wire rope 15 to pull the first spring 24 and play a role in enlarging the stroke, such that the stretching length of the first spring 24 is increased, the spring coefficient is reduced, and the weight and movement burden of the first spring 24 are reduced.
[0037] When the human walks with the exoskeleton, the working process of the exoskeleton may be divided into three phases, which are an energy storage phase, an energy release phase, and a transition phase.
[0038] During the energy storage phase, the walking gait is at the terminal swing, the ratchet wheel 18 and the pawl 13 are in an unengaged state, the left end of the foot rod member 17 starts to make contact with the ground, and under the action of the ground reaction force, the foot rod member 17 rotates clockwise to pull the traction steel wire rope 15, the first spring 24 is gradually stretched along the spring guide sleeve 25 under the action of the traction steel wire rope 15. From the terminal swing to the mid stance, the energy storage phase of the exoskeleton is finished, the protruded second cylinder 27 on the rotating disc 10 which moves along with the thigh rod member 6 enables the position adjusting column body 20 to rotate clockwise, the pawl 13 is driven to rotate counterclockwise around the axis so as to be engaged with the ratchet wheel 18 to perform gravitational potential energy locking, and at the moment, the foot is in full contact with the ground, and the first spring 24 is in the longest stretched state. As the pawl 13 and the ratchet wheel 18 are in an engaged state, the chain transmission fails at this time, and the crank connecting rod 14 connected to the large sprocket 23 is at the uppermost extreme position. [0039] During the energy release phase, the first spring 24 gradually shortens to release energy for power-assisting the hip joint. The ratchet wheel 18 and the pawl 13 are in an engaged state, the crank connecting rod 14 is in a relative static state in this process due to the failure of the chain transmission, and the lower end of the crank connecting rod 14 moves linearly with respect to the thigh rod member 6 under the pulling force of the first spring 24. In this process, the crank connecting rod 14 rotates counterclockwise around its upper end point, and the force applied to the side surface of the spring guide sleeve 25 by the crank connecting rod 14 and the first spring 24 is used for power-assisting the leg lifting process. When the process of power assistance by energy release is finished, the hip joint reaches the maximum movement angle, the protruded first cylinder 26 on the rotating disc 10 which moves with the thigh rod member 6 enables the position adjusting column body 20 to rotate counterclockwise, such that the pawl 13 is enabled to rotate clockwise around the axis to be disengaged from the ratchet wheel 8 to release the energy, and at the moment, the first spring 24 is at its original length.
[0040] During the transition phase, after the energy release process is finished, the walking gait is at the initial-mid swing, the pawl 13 and the ratchet wheel 18 are in a disengaged slate, the chain transmission recovers to work, and before the foot touches the ground, the crank connecting rod 14 rotates clockwise along with the large sprocket 23. After the sole touches the ground, another energy storage phase is started, the first spring 24 is stretched, the crank connecting rod 14 moves counterclockwise, and at the final phase of the energy storage phase, the crank connecting rod 14 returns to the uppermost extreme position again, and the angle between the thigh rod member 6 and the waist rod member 5 is gradually increased until the ratchet wheel 18 is engaged with the pawl 13, thus starting the next cycle.
[0041] In the whole phase, the gravitational potential energy during walking can be effectively used for power-assisting a user, and furthermore, by means of a locking mechanism, the energy can be released during lea lifting, i.e., the swing phase, after being stored at the walking stance phase, which improves the coupling between an exoskeleton and human body movement.
[0042] The above description is an explanation of the present disclosure rather than limiting the present disclosure. The scope of the present disclosure as defined herein is referred to in the claims and may be modified in any form within the scope of protection of the present disclosure.