CN113858180B - A magnetorheological joint for lower extremity exoskeleton - Google Patents

Abstract

The invention relates to a magneto-rheological joint for lower limb exoskeleton. The lower limb exoskeleton includes waist, thigh, knee joint, calf and foot. The knee joint is a magnetorheological joint structure with two large bevel gears inside. , a small bevel gear, magnetorheological bearings, flywheel and other structures. Both large bevel gears mesh with small bevel gears, and the transmission direction is vertical. Two magneto-rheological bearings are installed between each large bevel gear and the shaft, and a coil is wound between the two bearings. There is a flywheel on the shaft where the pinion gear is located, and two magneto-rheological bearings and a coil are also installed between the flywheel and the shaft. The damping of the rotation of the magneto-rheological bearing can be controlled by passing current into the coil, thereby controlling the resistance of the exoskeleton of the leg when it moves. This kind of lower extremity exoskeleton using magneto-rheological joints does not need motors, has the characteristics of low power consumption, long working time, low cost, and multi-function, and can solve the problems of energy and battery life of traditional motor-driven exoskeletons.

Description

A magnetorheological joint for lower extremity exoskeleton

technical field

The invention belongs to the field of intelligent robots, and in particular relates to a magneto-rheological joint structure for lower extremity exoskeleton.

Background technique

In recent years, exoskeleton technology has been greatly developed in the civilian field and has applications in many fields. In the medical field, it can be used for repetitive rehabilitation training. In the field of helping the elderly, it can be used to assist the elderly to walk. In the fields of rescue and logistics, it can be used to improve people's weight-bearing capacity. However, this type of motor-driven exoskeleton often consumes a lot of power. When using batteries as energy sources, the working time is usually only a few hours, and then it needs to be charged.

Magnetorheological fluid is a special material whose properties can be controllably changed by an external magnetic field. Magneto-rheological fluids are usually carried by non-magnetic fluid media, in which magnetic particles are suspended. When there is no external magnetic field, the magnetorheological fluid exhibits the properties of a general fluid and has strong fluidity; when an external magnetic field is applied, the magnetic particles are in close contact with each other under the action of the magnetic field, and the viscosity increases, so that the magnetorheological fluid exhibits solid-like properties. Under the control of the magnetic field, the transition between the liquid state and the solid state of the magnetorheological fluid is very fast, and the viscosity change in the process has the characteristics of stepless, reversible, fast, controllable, and low energy consumption. Therefore, it is used in sports equipment, medical It is widely used in equipment, vehicles, sealing and other fields. Applying magnetorheological technology to the control of lower extremity exoskeleton can greatly reduce the power consumption of lower extremity exoskeleton and prolong the working time.

Contents of the invention

The purpose of the present invention is to overcome the shortage of short working time of the existing exoskeleton, apply magnetorheological technology to the field of lower extremity exoskeleton, and propose a lower extremity exoskeleton with the characteristics of low power consumption, long working time, low cost, and multiple functions. skeleton. Most lower extremity exoskeletons use motors to control the joints. In terms of electrical energy, these exoskeletons use batteries to power the motors due to portability requirements. However, due to the limitation of the specific capacity of the battery and the large power consumption of the motor, usually the battery cannot support the motor to work for a long time. The lower extremity exoskeleton using magneto-rheological joints does not need a driving motor, so the power consumption is greatly reduced, and only a small power is used on the coil, and the use time is greatly prolonged under the same battery power supply. At the same time, without motors, the cost of the exoskeleton can also be reduced. In addition, this lower extremity exoskeleton using magneto-rheological joints can achieve a variety of different functions, such as leg lifting assistance, cushioning protection, and jump enhancement.

In order to achieve the above object, the technical solution adopted by the present invention is: a magneto-rheological joint for lower extremity exoskeleton, the magnetorheological joint includes two large bevel gears, a small bevel gear, a flywheel, a magneto-rheological bearing, and a ring coil , gearbox, first shaft and output shaft, case; where:

In the magneto-rheological joint, the two large bevel gears are connected to the first shaft through two magneto-rheological bearings, and a coil is sandwiched between the two magneto-rheological bearings; each large bevel gear meshes with a small bevel gear transmission;

Two magneto-rheological bearings and coils are also distributed between the shafts of the flywheel and the bevel pinion in the magneto-rheological joint;

The casing of the gearbox in the magneto-rheological joint is connected and fixed to the box body.

Further, it also includes waist exoskeleton, thigh exoskeleton, calf exoskeleton, and foot exoskeleton.

Further, the magneto-rheological joint is connected with the exoskeleton of the thigh by a key.

Further, four holes are distributed symmetrically at the bottom of the box of the magnetorheological joint, and the upper part of the calf exoskeleton is a flat plate with four holes of the same size, and the bottom of the box and the calf exoskeleton are connected by screws.

Further, the gearbox connects the first shaft and the output shaft, and maintains the rotational speed ratio of the two shafts at a certain value.

Further, the damping of the ball movement in the magneto-rheological bearing is controlled by the current in the coil, the damping is the smallest when the current is zero, and the greater the current, the greater the damping.

Furthermore, the inner and outer rings of the magneto-rheological bearing, the shaft and the gears are respectively provided with interference fits.

Furthermore, when the first shaft, the output shaft and the box rotate relative to each other, the bevel gear transmission makes the flywheel rotate, and the flywheel can store energy; this part of energy can be released later to drive the rotation of the shaft.

Further, the magnetorheological bearing is obtained by injecting magnetorheological fluid into the deep groove ball bearing.

Further, the rotation direction of the small bevel gear is changed by controlling the on-off of the current in the lower coil of the two large bevel gears.

Beneficial effect:

This kind of lower extremity exoskeleton using magneto-rheological joints does not need to use motors. Compared with traditional motor-driven exoskeletons, it has the characteristics of low power consumption, long working time, low cost, and multi-function, and can solve the problem of traditional motor-driven exoskeletons. The exoskeleton has problems in energy and battery life.

Description of drawings

Fig. 1 is exoskeleton model;

Figure 2 is a structural diagram of a magneto-rheological joint.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described below in conjunction with the drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

A magnetorheological joint for lower extremity exoskeleton, including waist exoskeleton (1), thigh exoskeleton (2), magnetorheological joint (3), calf exoskeleton (4), foot exoskeleton bones (5). The magnetorheological joint (3) includes two large bevel gears (6), a small bevel gear (7), a flywheel (8), a magnetorheological bearing (9), a ring coil (10), a gearbox (11), a A shaft (12), an output shaft (14), and a casing (13). in:

In the magnetorheological joint (3), the two large bevel gears (6) are connected to the first shaft (12) through two magnetorheological bearings (9) respectively, and the middle of the two magnetorheological bearings (9) A coil (10) is clamped. Two large bevel gears (6) are meshed with small bevel gears (7) for transmission.

Two magnetorheological bearings (9) and coils (10) are also distributed between the shafts of the flywheel (8) and the pinion bevel gear (7) in the magnetorheological joint (3).

The casing of the gearbox (11) in the magneto-rheological joint (3) is connected with and fixed to the box body (13).

The thigh exoskeleton (2) and the magneto-rheological joint (3) are positioned by key connection;

The magnetorheological joint (3) is connected and fixed to the lower leg exoskeleton (4) by screws.

The gearbox (11) maintains the rotational speed ratio of the two shafts (12), (14) at a certain value.

An interference fit is adopted between the inner and outer rings of the magnetorheological bearing (9) and the shaft and gear to ensure the fixation of the circumferential position between the inner and outer ring of the bearing and the shaft and gear.

The magnetorheological bearing (9) is obtained by injecting magnetorheological fluid into the deep groove ball bearing.

The damping of ball movement in the magnetorheological bearing (9) is controlled by the magnitude of the current in the coil. When the current is zero, there is no external magnetic field at the magnetorheological fluid, and the ball movement damping is the smallest; when the current is large, the magnetorheological Under the action of an external magnetic field, the fluidity of the liquid is small, and the damping of the ball motion is relatively large.

The direction of rotation of the small bevel gear (7) can be controlled by changing the on-off current of the coil (10) in the two large bevel gears (6), the two coils (10) a, b, a are energized and b is de-energized, The direction of rotation of the pinion bevel gear is opposite to that of a power-off b power-on.

The working principle of the present invention is: when the thigh and calf of the exoskeleton are relatively rotated, the inner coil of a large bevel gear (6) is energized, the magnetorheological bearing is in a large damping state, and the large bevel gear (6) is fixed relative to the shaft, driving The small bevel gear (7) rotates, and now the coil at the flywheel (8) is energized, and the rotation of the gear shaft of the small bevel gear (7) drives the flywheel (8) to rotate together, and kinetic energy is stored in the flywheel (8); Turn on the electric current of the inner coil of the bevel gear (6), and at the same time energize the coil in the other bevel gear (6), and the flywheel will drive the small bevel gear (7) to rotate, and then drive the large bevel gear with the coil energized to rotate, thus The kinetic energy of the flywheel can be released to promote the rotation of the shaft where the large bevel gear is located. In addition, a gearbox (11) is added between the output shaft (14) of the magneto-rheological joint (14) and the first shaft (12) where the bevel gear (7) is located, to increase the distance between the first shaft (12) and the output shaft (14). The speed ratio between them increases the capacity of the flywheel to store energy. In addition, when there is energy stored in the flywheel (8) but does not need to be released immediately, the current of the inner coil of the flywheel can be disconnected, so that the flywheel is idling, and the rotation of the small bevel gear (7) is not affected, and this part of energy needs to be released When power is applied to the coil again, the flywheel will drive the small bevel gear (7) to rotate, and then drive the axis where the large bevel gear (6) is located to rotate and perform work outwards. In addition, if the coils in the two large bevel gears (6) are energized at the same time, since the small bevel gear (7) rotates, the rotation directions of the two large bevel gears (6) meshing with the small bevel gear are originally opposite. After the current is applied, the damping between the two large bevel gears and the shafts increases sharply, and the rotation direction tends to be the same. Therefore, under the two contradictory restrictions, the large bevel gears will be difficult to rotate, and the magneto-rheological joint is in a large damping state. In this state, the lower extremity exoskeleton can play a supporting and cushioning role.

According to an embodiment of the present invention, a magnetorheological joint is proposed. In the magnetorheological joint (3), the two parts of the box (13) are symmetrical, and the two parts are attached and fixed on the top of the calf during assembly. The inner ring of the magneto-rheological bearing (9) inside the joint and the shaft, the outer ring and the bevel gear or the flywheel are all interference fits, thereby playing the role of positioning. The magnetorheological bearing (9) is obtained by removing the bearing sealing ring, cleaning and removing lubricating oil, injecting magnetorheological fluid, and sealing it well.

Ring-shaped protrusions are left on the perforated part of the case body (13) of the magneto-rheological joint (3) to prevent large-area friction between the bearing, the bevel gear and the case body wall. The corresponding position of the coil on the first shaft (12) has a cut-off part length, which facilitates the positioning of the coil on the one hand, and on the other hand reduces the grinding area on the gear shaft and reduces the processing cost.

In the magneto-rheological joint (3), a groove is left on the inner circular surfaces of the large bevel gear (6) and the flywheel (8), which is used to provide an external passage for the coil (10).

In the embodiments where the present invention is used for lower limb rehabilitation training or lower limb assisting, the working process is roughly as follows: when the patient or the porter squats down, there is a relative rotation angle between the thigh and the calf, which can drive the magneto-rheological joint (3 ) relative to the rotation of the box body, at this time one of the internal magneto-rheological bearings (9) of the two large bevel gears is in a solidified state, and the large bevel gear (6) is in a connected state, and the first shaft (12) There is no relative rotation between them, and the rotation of the shaft is transmitted to the rotation of the shaft where the flywheel (8) is located through the meshing transmission of the large and small bevel gears. At this time, the flywheel rotates and stores kinetic energy; The inner coil of the large bevel gear in the state is powered off, and the inner coil of the other large bevel gear (6) is energized, and the rotation of the shaft where the flywheel is located is transmitted to the shaft where the large bevel gear is located through the meshing of the bevel gear, so that the output shaft (14) rotates in the opposite direction, thereby It drives the thigh and calf to move in the opposite direction of rotation, so it can give the leg an upward boost when people need to stand up. Therefore, for patients who can't independently complete squat-stand up and porters who have difficulty standing up when carrying goods, the present invention can collect energy when they squat down, and release the energy when they stand up, giving legs Lifting provides assistance to assist in the completion of lower limb rehabilitation training or cargo handling.

In embodiments where the present invention is used for high-altitude jumping protection, squatting support cushioning and Chairless-Chair, the working process is roughly as follows: when people need to jump from a certain height to the ground due to emergency avoidance or performing special tasks, they wear this chair When the lower extremity exoskeleton described in the invention jumps off, when it comes into contact with the ground, the two large bevel gears (6) in the magneto-rheological joint (3) are in a connected state, and the entire magnetorheological joint is in a large damping state, and the magnetic flow The rotation of the inner shaft of the variable joint requires huge torque to push, so the kinetic energy of a person jumping off will be consumed in the rotational motion of the magneto-rheological bearing (9) during the relative rotation of the large and small legs, thereby reducing the distance between the person and the ground. The impact of the impact can have a protective effect on people who jump from high altitude. Similarly, when a person carries a heavy object and puts it down, there will be a large impact. When using the lower extremity exoskeleton of the present invention, the magneto-rheological joint (3) is in a large damping state, and the gravitational potential energy in the process of lowering the heavy object is consumed During the rotation of the bearing, the impact of the heavy objects can be reduced, which can play a buffer role in the process of carrying the heavy objects, and can greatly reduce the difficulty of carrying and putting down the goods. Similarly, for workers who need to bend their knees and squat for a long time, when using the lower extremity exoskeleton of the present invention, the magneto-rheological joint (3) is in a large damping state at a given posture, and the lower extremity exoskeleton will provide support , at this time, the weight of the human body cannot make the magneto-rheological bearing (9) rotate, and the lower extremity exoskeleton is similar to a Chairless-Chair, acting as a chair, allowing people to sit down anytime and anywhere, and can adjust the sitting position posture, thereby greatly reducing the burden on the body of workers who bend their knees for a long time.

In addition, the present invention can also function as a jump enhancement. Before jumping, repeat squatting for many times. During this process, a large bevel gear (6) in the magneto-rheological joint (3) is in a connected state, and the inner coil of the other large bevel gear is powered off and is in an idling state. The flywheel ( 8) In the connected state when squatting, in the idle state when standing up. In the process of squatting many times, the flywheel has been storing energy and increasing kinetic energy; when jumping later, this energy is released at one time to push the legs up and assist the jumping process, so that people can jump faster high.

If the flywheel in the magneto-rheological joint is connected with a motor, other functions can also be realized. For example, the increase of the step frequency of the robot: the walking process of the traditional robot is driven by the motor's non-stop forward and reverse rotation, but the motor's rotor motion damping is small, and the rotor cannot stop immediately due to inertia after changing the direction of the current, which requires a certain effect It takes time to stop, and the acceleration of the rotor also takes a certain amount of time when reversing, so the step frequency of the robot is often not high. When the exoskeleton of the present invention is used, the motor can be continuously rotated in one direction. The large bevel gear connected to the shaft (12) switches the rotation direction of the output shaft, thereby realizing the increase of the step frequency of the robot. There is also the positioning of the motor. The traditional motor will vibrate after reaching the required position, and it will take a long time to stop. If the structure shown in the present invention is adopted, the motor is connected with the flywheel. When the motor is about to reach the designated position, the two Large bevel gear (6) is all in connection state, and the damping that the motor that is connected with flywheel rotates increases greatly, and the stopping of motor is just more rapid. Therefore, the positioning of the motor can be made more rapid and accurate.

During the installation process, first install a magneto-rheological bearing to a specified position on the first shaft (12), then place a coil (10) of a certain thickness next to the bearing, and then install another magnetorheological bearing next to the coil , and then install the large bevel gear (6) on the outer side of the bearing, fix it by interference fit, and then install the bearing, coil, bevel gear on the other side and the bearing, coil, Flywheel, box body is put together at last, screw on the plane that is fixed on the exoskeleton shank (4) top. The gearbox is fixed to one side of the box, and the two shafts are on a straight line. The high-speed output shaft of the gearbox is connected to the first shaft (12) of the box, and the low-speed output shaft is connected to the bottom of the exoskeleton thigh (2) through a flat key. The shaft holes are connected, so that the magneto-rheological joint (3) is assembled and connected with the lower extremity exoskeleton. The present invention is completed.

Although the illustrative specific embodiments of the present invention have been described above, so that those skilled in the art can understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, As long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are included in the protection list.

Claims (10)

1. A magneto-rheological joint for lower extremity exoskeleton, characterized in that: The magnetorheological joint includes two large bevel gears, a small bevel gear, a flywheel, a magnetorheological bearing, a coil, a gearbox, a first shaft and an output shaft, and a box; the coil is a ring coil; wherein: In the magneto-rheological joint, the two large bevel gears are connected to the first shaft through two magneto-rheological bearings, and a coil is sandwiched between the two magneto-rheological bearings; each large bevel gear meshes with a small bevel gear transmission; Two magneto-rheological bearings and coils are also distributed between the shafts of the flywheel and the bevel pinion in the magneto-rheological joint; The casing of the gearbox in the magneto-rheological joint is connected and fixed to the box body. 2 . The magneto-rheological joint for lower extremity exoskeleton according to claim 1 , further comprising a waist exoskeleton, a thigh exoskeleton, a calf exoskeleton, and a foot exoskeleton. 3 . The magneto-rheological joint for lower limb exoskeleton according to claim 2 , wherein the magnetorheological joint is connected with the thigh exoskeleton by keys. 4 . 4. The magnetorheological joint for lower limb exoskeleton according to claim 2, characterized in that, the bottom of the box of the magnetorheological joint is symmetrically distributed with 4 holes, and the upper part of the calf exoskeleton has 4 holes of the same size The flat plate, the bottom of the box and the calf exoskeleton are connected by screws. 5. The magneto-rheological joint for lower extremity exoskeleton according to claim 1, characterized in that the gearbox connects the first shaft and the output shaft, and maintains the speed ratio of the two shafts at a certain value. 6. The magnetorheological joint for lower extremity exoskeleton according to claim 1, characterized in that the damping of ball motion in the magnetorheological bearing is controlled by the current in the coil, the damping is the smallest when the current is zero, and the greater the current , the greater the damping. 7 . The magneto-rheological joint for lower extremity exoskeleton according to claim 1 , characterized in that the inner and outer rings of the magnetorheological bearing, the shaft and the gears respectively adopt interference fit. 8. The magneto-rheological joint for lower extremity exoskeleton according to claim 1, characterized in that, when the first shaft, the output shaft and the box rotate relative to each other, the bevel gear transmission makes the flywheel rotate, and the flywheel can store energy; this part The energy can then be released to drive the rotation of the shaft. 9 . The magnetorheological joint for lower limb exoskeleton according to claim 1 , wherein the magnetorheological bearing is obtained by injecting magnetorheological fluid into deep groove ball bearings. 10. The magneto-rheological joint for lower extremity exoskeleton according to claim 1, wherein the rotation direction of the small bevel gear is changed by controlling the on-off of the current in the lower coil of the two large bevel gears.

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