TWI495460B - Elastic actuator with actively variable stiffness, method and human exoskeleton thereof - Google Patents

Description

Differential drive active variable stiffness elastic system, method thereof and human external bone

The present invention relates to an exoskeleton system, and more particularly to an exoskeleton system for actively adjusting its output shaft rigidity.

Due to advances in technology and market demand, many different uses of exoskeleton systems have been developed to assist humans in a variety of different tasks, the most common of which are muscle rehabilitation systems, prosthetic limbs and various robots. However, most of the exoskeleton systems provide powerful power to assist humans in various activities, but lack a safe human-machine interface. Therefore, when a user wears a skeletal system other than the conventional technique and interacts with other people, it is easy to accidentally hurt the other party.

In order to solve this problem, several types of rigid exoskeleton systems have been proposed. One of the prior art exoskeleton systems is capable of individually controlling the rigid adjustment mechanism of the exoskeleton system using a single motor. Although this method can also adaptively adjust the rigidity of the output shaft of the exoskeleton system, however, since its rigid adjustment mechanism requires an additional motor to operate, this motor cannot simultaneously be used to provide power to the output shaft of the exoskeleton system. Therefore, it also causes an increase in cost and a decrease in energy use efficiency.

On the other hand, the rigid adjustment mechanism of the skeletal system of the prior art is usually complicated, which also leads to an increase in the volume of the exoskeleton system, which not only increases the cost, but also is extremely difficult to maintain, and is extremely inconvenient to use.

Therefore, how to propose an exoskeleton system that can actively adjust the rigidity of its output shaft, provide greater output power, and has a simpler structural design, higher energy efficiency and lower cost. The problem to be solved by the present invention.

In view of the above-mentioned problems of the prior art, one of the objects of the present invention is to provide a differential drive active variable rigidity elastic system to solve the conventional technique that the skeletal system cannot actively adjust the rigidity of the output shaft, and the energy use efficiency is not Good, complex construction, high cost and excessive volume.

According to one of the objects of the present invention, a differential drive active variable stiffness elastic system is proposed. The system can include a central shaft, a first worm gear, a second worm gear, an output shaft, a stiffness adjustment device, and a linkage. The first worm wheel is coupled to the central shaft. The second worm wheel is coupled to the first worm wheel through a central shaft. The output shaft is placed at the output of the central axis. Wherein, when the first and second worm wheels rotate in the same direction, the central shaft is driven to drive the output shaft to rotate; and when the first and second worm wheels rotate in the opposite direction, the linkage device is driven to drive the first and second engagement The box slides along the elastic piece toward the central axis or slides to both ends of the elastic piece, so that the effective length of the elastic piece is changed to adjust the rigidity of the output shaft.

According to another object of the present invention, a method for actively adjusting the rigidity of an output shaft of an elastic system is provided. The method may include the steps of: providing a central shaft and connecting the central shaft to a first worm wheel and a second worm wheel; providing an output shaft And disposed at the output end of the central shaft; providing a rigidity adjusting device, the rigid adjusting device comprises at least an elastic piece, a first connecting box and a second connecting box, the center of the elastic piece is fixed on the central axis between the two worm wheels, the first The first and second adapter boxes are slidably respectively sleeved on the two elastic sheets Providing a connecting rod device for connecting the connecting rod device to the first worm wheel, the second worm wheel, the first connecting box and the second connecting box; driving the central shaft to drive the output by driving the first and second worm wheels to rotate in the same direction Rotation of the shaft; and by driving the first and second worm wheels to rotate in reverse, driving the link device to drive the first and second adapter boxes to slide along the elastic piece toward the central axis or to slide toward the ends of the elastic piece to make the elastic The effective length of the sheet is changed to adjust the stiffness of the output shaft.

Preferably, the system further includes a first sliding table and a second sliding table, and the first and second sliding tables are disposed in parallel on one side of the first worm wheel.

Preferably, the system further includes a first sliding member guide post and a second sliding member guiding column, and the first and second sliding member guiding columns are slidably disposed on the first sliding table and the second sliding table, respectively.

Preferably, the system further includes a third sliding table and a fourth sliding table, and the third and fourth sliding tables are disposed on one side of the second worm wheel corresponding to the first and second sliding tables.

Preferably, the system further comprises third and fourth sliding member guide columns, and the third and fourth sliding member guiding columns are slidably disposed on the third and fourth sliding tables, respectively.

Preferably, the link device can include a first link set and a second link set.

Preferably, the first link set may include a first link and a second link, and a first end of the first link may be pivoted on one side of the first end of the second link, and the other side may be The second connecting end of the first connecting rod is pivotally disposed on the first connecting box; the other end of the first end of the second connecting rod is pivotally disposed on the third sliding member guiding post, The second end of the two links can be pivoted to the second junction box.

Preferably, the second link set may include a third link and a fourth link, and one side of the first end of the third link may be pivoted at the first end of the fourth link, and the other side may be pivoted a second sliding member guide post, the second end of the third connecting rod is pivotally disposed on the second connecting box; the other end of the first end of the fourth connecting rod is pivotally disposed on the fourth sliding member guiding column, and the fourth connecting rod The second end can be pivoted to the first junction box.

Preferably, the first and second adapter boxes respectively comprise at least one roller, and the roller can be disposed between the first and second connection boxes and the elastic piece.

Preferably, the first and second worm wheels are respectively combined by the same two sub-worm wheels, and the worm teeth of the two sub-worm wheels are mutually staggered to eliminate the backlash of the first and second worm wheels.

According to still another object of the present invention, a differential drive active variable stiffness elastic system is proposed. The system includes a central shaft, a first worm gear, a second worm gear, an output shaft, a stiffness adjustment device, and a linkage device. The first worm wheel is coupled to the central shaft. The second worm wheel is coupled to the first worm wheel through a central shaft. The output shaft is placed at the output of the central axis. The rigid adjusting device comprises a plurality of elastic pieces and a plurality of connecting boxes corresponding to the respective elastic pieces, one end of each elastic piece is fixed on a central axis between the two worm wheels, and each of the connecting boxes is slidably respectively sleeved on the corresponding each The other end of the elastic piece. The connecting rod device is coupled to the first worm wheel, the second worm wheel and each of the connecting boxes. The connecting rod device is coupled to the first worm wheel, the second worm wheel, and the respective adapter boxes. Wherein, when the first and second worm wheels rotate in the same direction, the central shaft is driven to drive the output shaft to rotate; and when the first and the second worm wheel rotate in the opposite direction, the linkage device is driven to drive each of the adapter boxes simultaneously Each of the elastic pieces slides toward the central axis or slides away from the central axis, so that the effective length of each elastic piece is changed to adjust the rigidity of the output shaft.

According to still another object of the present invention, a human external bone is provided that can be carried on a human body to assist human body action. The human external bone can include an elastic system and a power supply, and the elastic system can have the above structure and function.

In view of the above, the differentially driven active variable rigid elastic system, the method thereof and the human external bone thereof according to the present invention may have one or more of the following advantages:

(1) The differential drive active variable rigidity elastic system of the present invention can actively adjust the rigidity of its output shaft, and therefore, in addition to achieving better positioning control, can safely interact with humans.

(2) The differential drive active variable rigidity elastic system of the present invention can simultaneously adjust the rigidity of the output shaft of the elastic system by a simple structure, thereby reducing the manufacturing cost and complexity of the system.

(3) The differential drive active variable rigid elastic system of the present invention can drive two worms respectively by two motors to drive the two worm wheels to rotate in the same direction or in opposite directions, thereby driving the output shaft to rotate or adjust the rigidity of the output shaft. Therefore, the power of the output shaft can be provided by the two motors, so that the output torque of the system can be effectively improved, and the energy utilization can be more efficient.

(4) The worm gear system of the differential drive active variable rigidity elastic system of the present invention is composed of the same two sub-worm gears, and the worm gear teeth of the two sub-worm wheels are interlaced, thereby eliminating the back reserved for the worm wheel production. The effect of the gap.

(5) The differential drive active variable rigidity elastic system of the present invention has a small volume, and therefore has a large elasticity in use.

1‧‧‧Differential drive active variable stiffness system

2‧‧‧Exoskeleton system

11‧‧‧ center axis

111‧‧‧ Output

12‧‧‧First Worm Gear Set

121‧‧‧First worm gear

122‧‧‧First worm

1211‧‧‧First slide table

1212‧‧‧Second slide table

1213‧‧‧First slide guide column

1214‧‧‧Second slider guide post

13‧‧‧Second worm gear set

131‧‧‧Second worm gear

132‧‧‧second worm

1311‧‧‧The third sliding table

1312‧‧‧fourth sliding table

1313‧‧‧Three slider guide posts

1314‧‧‧4th sliding guide column

14‧‧‧First Link Group

141‧‧‧first link

142‧‧‧second link

15‧‧‧Second linkage

151‧‧‧ Third Link

152‧‧‧fourth link

16‧‧‧Rigid adjustment device

161‧‧‧First connection box

162‧‧‧Second connection box

163‧‧‧Elastic film

164‧‧‧Roller

165‧‧‧Fixed parts

17‧‧‧ Output shaft

181, 182‧‧ ‧ motor

19‧‧‧Shell

A, B‧‧‧ sub-worm wheel

S151~S156‧‧‧Step procedure

1 to 4 are respectively a first, second, third and fourth schematic view of the first embodiment of the differential drive active variable rigidity elastic system of the present invention.

Figure 5 is an exploded view of the first embodiment of the differential drive active variable stiffness elastic system of the present invention.

Figures 6-9 are the first, second, third and fourth schematic views of the four-bar linkage system of the differential drive active variable stiffness elastic system of the present invention, respectively.

Figure 10 is a schematic view showing the structure of a worm wheel of the first embodiment of the differential drive active variable rigidity elastic system of the present invention.

Figure 11 is a schematic view showing the application of the differential drive active variable rigid elastic system of the present invention to human bones.

Figures 12 to 14 are first, second and third schematic views respectively showing the principle of operation of the differentially driven active variable rigid elastic system of the present invention.

Figure 15 is a flow chart showing a method for actively adjusting the rigidity of the output shaft of the elastic system of the present invention.

Hereinafter, embodiments of the differentially driven active variable rigid elastic system, the method thereof and the human external bone thereof according to the present invention will be described with reference to the related drawings. For ease of understanding, the same components in the following embodiments are identical. Symbols are indicated to illustrate.

Please refer to FIGS. 1~5, and FIGS. 1~4 are respectively the first, second, third and fourth schematic views of the first embodiment of the differential drive active variable rigid elastic system of the present invention, and FIG. 5 is a schematic view. An exploded view of a first embodiment of the inventive differentially driven active variable stiffness elastic system. As shown, the differential drive active variable stiffness elastic system 1 of the present invention may include a central shaft 11, a first worm gear set 12, a second worm gear set 13, a stiffness adjustment device 16, an output shaft 17, and a first connection A four-bar linkage consisting of a rod set 14 and a second link set 15.

In the present embodiment, the central shaft 11 connects the first worm worm gear set 12 and the second worm worm gear set 13, and the output end 111 of the central shaft 11 is provided with an output shaft 17. The first worm gear set 12 can include a first worm gear 121, a first worm 122, and a motor 181, and the second worm gear set 13 can include a second worm gear 131, a second worm 132, and a motor 182. As shown in FIG. 4, the elastic system 1 can be disposed in the housing 19, and the first worm 122 and the second worm 132 can be driven by a motor 181 and 182, respectively, thereby driving the first worm wheel 121 and the second worm wheel 131 to rotate. .

The first sliding table 1211 and the second sliding table 1212 are disposed on one surface of the first worm wheel 121. The first sliding table 1211 and the second sliding table 1212 are disposed in parallel on one surface of the first worm wheel 121. The first sliding table 1211 and the second sliding table 1212 are respectively provided with a first sliding member guide post 1213 and a second sliding member guiding column 1214. The two sliding member guiding columns are slidably disposed on the first sliding table 1211, respectively. And on the second sliding table 1212. Similarly, a third sliding table 1311 and a fourth sliding table 1312 may be disposed on one surface of the second worm wheel 131. The third sliding table 1311 and the fourth sliding table 1312 may be disposed in parallel on one surface of the second worm wheel 131. The third sliding table 1311 and the fourth sliding table 1312 are respectively disposed on the third sliding member guide 1313 and the fourth sliding member guiding column 1314. The two sliding member guiding columns are slidably disposed on the third sliding table 1311, respectively. And the fourth sliding table 1312.

The rigidity adjusting device 16 may include an elastic piece 163, a first connecting box 161, and a second connecting box 162. As shown in FIG. 5, the central axis 11 is recessed to form an accommodating space, and the center of the elastic piece 163 is fixed to the center of the central axis 11 between the first worm wheel 121 and the second worm wheel 131 through a fixing member 165. In the space. The first connecting box 161 and the second connecting box 162 are slidably disposed at the two ends of the elastic piece 163. The first connecting box 161 and the second connecting box 162 can further be provided with a plurality of rollers 164 to reduce The frictional force generated when the first adapter box 161 and the second adapter box 162 slide along the elastic piece 163. The relative positions of the first connecting box 161 and the second connecting box 162 on the elastic piece 163 may determine the effective length of the elastic piece 163. The elastic piece 163 may be a leaf spring or may be formed by stacking a plurality of elastic pieces.

The four-bar linkage used in the present embodiment includes the first link set 14 and the second link set 15. The first link set 14 can include a first link 141 and a second link 142. One side of the first end of the first link 141 is pivotally disposed on one side of the first end of the second link 142, and the other end of the first end of the first link 141 is pivotally disposed on the first slider guide 1213 The second end of the first link 141 is pivotally disposed on the first connecting box 161; the other end of the first end of the second link 142 is pivotally disposed on the third slider guide 1313, and the second link 142 The second end is pivoted to the second junction box 162. The second link set 15 can include a third link 151 and a fourth link 152. One side of the first end of the third link 151 can be pivoted to the first end of the fourth link 152, and the other end of the first end of the third link 151 can be pivoted with the second slide guide 1214, third The second end of the connecting rod 151 is pivotable The other end of the first end of the fourth link 152 is pivotally disposed on the fourth sliding member guide post 1314, and the second end of the fourth connecting rod 152 is pivotally disposed on the first connecting box 161. . Of course, the connecting rod device can also be in other forms, and the invention is not limited thereto.

The elastic system 1 can drive the first worm 122 and the second worm 132 to rotate through the motors 181 and 182, respectively, to drive the first worm wheel 121 and the second worm wheel 131 to rotate. When the rotation angles of the first worm wheel 121 and the second worm wheel 131 are the same, the central shaft 11 can be driven to drive the output shaft 17 to rotate. Therefore, the torque of the output shaft 17 is simultaneously supplied by the motors 181 and 182.

When the rotation angles of the first worm wheel 121 and the second worm wheel 131 are different, the first worm wheel 121 and the second worm wheel 131 can drive the respective links through the sliding table and the slider guide column to drive the first adapter box 161. And the second adapter box 162 slides along the elastic piece 163 toward the central axis 11 or slides toward both ends of the elastic piece 163, respectively. When the first connecting box 161 and the second connecting box 162 are closer to the central axis 11, the effective length of the elastic piece 163 is shorter. At this time, the output shaft 17 can have lower rigidity, and the output shaft 17 can still be fixed. The amplitude swings from side to side, so it can interact safely with humans. On the other hand, when the first adapter box 161 and the second adapter box 162 are closer to the both ends of the elastic piece 163 as they are away from the central axis 11, the effective length of the elastic piece 163 is longer. At this time, the output shaft 17 can have a higher rigidity. Therefore, the output shaft 17 cannot swing left and right, but can provide greater torque and more precise positioning control.

Of course, the embodiment is merely an example, and the elastic system of the present invention may further include other various embodiments. For example, the rigidity adjusting device may further include a plurality of elastic pieces and a plurality of connecting boxes corresponding to the respective elastic pieces, one end of each elastic piece is fixed on a central axis between the two worm wheels, and each of the connecting boxes is slidably separately sleeved At the other end of each corresponding elastic piece. Each of the adapter boxes can be coupled to each of the worm gears by means of a link device. Similarly, when the first second worm wheel rotates in the same direction, the central shaft is driven to drive the output shaft to rotate; and when the first and second worm wheels rotate in the opposite direction, the linkage device is driven to drive each of the adapter boxes simultaneously. Each of the elastic pieces slides toward the central axis or slides away from the central axis to change the effective length of each elastic piece to adjust the rigidity of the output shaft of the elastic system.

It is worth mentioning that the conventional exoskeleton system requires a dedicated motor to control its rigid adjustment mechanism, and this exclusive motor cannot provide any power to its output shaft. Therefore, the energy use efficiency of the skeletal system of the prior art is low, and thus the manufacturing cost thereof is increased. In addition, the structure of the rigid adjustment mechanism of the skeletal system of the prior art is too complicated, so its volume is large, which is not only inconvenient to maintain, but also extremely expensive. However, the rigidity adjusting device of the differential drive active variable rigidity elastic system of the present invention can perform the adjustment of the rigidity of the output shaft without requiring a dedicated motor, thereby enabling more efficient use of energy. In addition, the rigidity adjusting device and the four-bar linkage device of the elastic system of the present invention have a simple structural design, thereby reducing the cost, being easy to maintain, and having a small volume. Therefore, the present invention has the progressiveness of patent requirements.

Please refer to FIGS. 6-9, which are first, second, third and fourth schematic views respectively of the four-bar linkage system of the differential drive active variable rigid elastic system of the present invention. θ 1 and θ 2 represent the rotation angles of the first worm wheel and the second worm wheel, respectively, and θ 0 represents the rotation angle of the elastic piece 163, and N represents the normal line of the elastic piece 163. As shown in FIG. 6 and FIG. 7, when the rotation angles of the first worm wheel and the second worm wheel are different, the first adapter box 161 and the second adapter box 162 are respectively moved along the two ends of the elastic piece 163 to make the elasticity The effective length of the sheet 163 becomes longer, and the rigidity of the output shaft of the elastic system is lowered. As shown in FIGS. 8 and 9, when the rotation angles of the first worm wheel and the second worm wheel are the same, the first adapter box 161 and the second adapter box 162 do not slide along the elastic piece 163, but the output shaft is Will turn.

Please refer to FIG. 10, which is a schematic structural view of a worm wheel of a first embodiment of the differential drive active variable rigidity elastic system of the present invention. As shown in the figure, the worm wheel of the differential drive active variable rigidity elastic system of the present invention can be respectively combined by using the same two sub-worm wheels A and B, and the worm gear teeth of the two sub-worm wheels A and B can be interlaced. The structure can effectively eliminate the influence of the backlash reserved during the production of the worm wheel, so that the worm wheel can run smoothly.

Please refer to FIG. 11 , which is a schematic diagram of the differential drive active variable rigid elastic system of the present invention applied to human bones. As shown in the figure, when the human exoskeleton 2 is used as a muscle rehabilitation system When used, if the patient wants to interact with the nursing staff, the rigidity of the output shaft of the external bone 2 can be reduced to protect the nursing staff who interact with the patient. When the patient wants to perform muscle rehabilitation, the rigidity of the output shaft of the human external bone 2 can be adjusted, so that the external bone 2 can provide greater torque and more precise positioning control. Of course, the above is only an example, and the differential drive active variable rigid elastic system of the present invention is more applicable to various other exoskeleton systems or used for military purposes.

In order to more detail the operating principles of the differentially driven active variable stiffness elastic system of the present invention, the concept of the present invention is illustrated by way of illustration. Please refer to Figures 12 to 14, which are respectively the first, second and third schematic diagrams of the operating principle of the differential drive active variable rigid elastic system of the present invention. As shown in Fig. 12, the present invention utilizes two motors to control the stiffness and displacement of the output shaft of the resilient system. F1 and F2 represent the input control points of the system, respectively. P is the center point between object 1 and object 2. S denotes the position of the P point before the external force is applied, and S' denotes the position of the P point after the external force is applied. D is the distance between the object 1 and the object 2 before the external force is applied, and D' is the distance between the object 1 and the object 2 after the external force is applied. The distance between object 1 and object 2 can represent the stiffness of the output shaft of the elastic system; the position of point P can represent the displacement of the output shaft. Therefore, when the object 1 and the object 2 advance at the same speed by the direction of the arrow, the position of the point P moves from S to S', and the distance between the object 1 and the object 2 remains unchanged, so that the output shaft of the elastic system can be rigid. Turn under the changing conditions.

As shown in Fig. 13, in the example 1, when the object 1 and the object 2 advance in opposite directions, the position of the point P does not change, and the distance between the object 1 and the object 2 changes from D to D', and therefore, the output of the elastic system The position of the axis does not change, but its stiffness changes. In contrast, in Example 2, the position of the output shaft of the elastic system changes, but its rigidity does not change.

As shown in Fig. 14, in Example 3, the rigidity and displacement of the output shaft of the elastic system were independently changed. In Example 4, the stiffness and displacement of the output shaft of the elastic system dynamically change.

Although the foregoing description of the method of actively adjusting the stiffness of the output shaft of the elastic system of the present invention has been described in the course of illustrating the differential drive active variable stiffness elastic system of the present invention, for the sake of clarity, the following is still drawn. The flow chart is described in detail.

Please refer to FIG. 15 , which is a flow chart of the method for actively adjusting the output shaft rigidity of the elastic system according to the present invention.

In step S151, a center shaft is provided, and the center shaft is coupled to the first worm wheel and the second worm wheel.

In step S152, an output shaft is provided and disposed at the output end of the central shaft.

In step S153, a rigidity adjusting device is provided. The rigidity adjusting device comprises at least an elastic piece, a first connecting box and a second connecting box. The center of the elastic piece is fixed on the central axis between the two worm wheels, and the first and second connecting The boxes are slidably sleeved on both ends of the elastic piece.

In step S154, a link device is provided to connect the link device to the first worm wheel, the second worm wheel, the first adapter box, and the second adapter box.

In step S155, the first and second worm wheels are driven to rotate in the same direction to drive the central shaft to drive the output shaft to rotate.

In step S156, by driving the first and second worm wheels to rotate in the opposite direction, the driving link device drives the first and second connecting boxes to slide toward the central axis or slide to both ends of the elastic piece, so that the elastic piece is effective. The length is changed to adjust the rigidity of the output shaft.

The detailed description and embodiments of the method of actively adjusting the output shaft rigidity of the elastic system of the present invention have been described above with respect to the differential drive active variable stiffness elastic system of the present invention, and will not be repeated here for the sake of brevity.

In summary, the differential drive active variable stiffness elastic system of the present invention can actively adjust the rigidity of its output shaft, so that in addition to achieving better positioning control, it is safer to interact with humans. In addition, the present invention can simultaneously adjust the rigidity of the output shaft of the elastic system by a simple structure, thereby reducing the manufacturing cost, complexity, and volume of the system. Furthermore, the present invention can drive the two worms by two motors to drive the two worm wheels to rotate in the same direction or in the opposite direction, thereby driving the output shaft to rotate or adjust the rigidity of the output shaft. Therefore, the power of this output shaft can be provided by two motors, so it can effectively The output torque of the high system makes energy utilization more efficient. In addition, the worm gear system used in the present invention is composed of the same two sub-worm gears, and the worm gear teeth of the two sub-worm wheels are interlaced, so that the influence of the backlash reserved during the production of the worm wheel can be eliminated. Thus, the present invention is indeed capable of effectively improving the shortcomings of the skeletal system of the prior art.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

1‧‧‧Differential drive active variable stiffness system

11‧‧‧ center axis

111‧‧‧ Output

121‧‧‧First worm gear

1211‧‧‧First slide table

1212‧‧‧Second slide table

1213‧‧‧First slide guide column

1214‧‧‧Second slider guide post

131‧‧‧Second worm gear

1311‧‧‧The third sliding table

1312‧‧‧fourth sliding table

1313‧‧‧Three slider guide posts

1314‧‧‧4th sliding guide column

141‧‧‧first link

142‧‧‧second link

151‧‧‧ Third Link

152‧‧‧fourth link

161‧‧‧First connection box

162‧‧‧Second connection box

163‧‧‧Elastic film

164‧‧‧Roller

165‧‧‧Fixed parts

Claims (22)

A differential drive active variable stiffness elastic system comprising: a central shaft; a first worm gear coupled to the central shaft; a second worm gear coupled to the first worm gear through the central shaft; an output shaft And a rigid adjusting device comprising at least one elastic piece, a first connecting box and a second connecting box, wherein the center of the elastic piece is fixed on the central axis between the two worm wheels The first adapter box and the second adapter box are slidably sleeved on opposite ends of the elastic piece; and a link device is coupled to the first worm wheel, the second worm wheel, and the first adapter box And the second adapter box; wherein, when the first worm wheel and the second worm wheel rotate in the same direction, the central shaft is driven to drive the output shaft to rotate; and when the first worm wheel and the second worm wheel rotate in opposite directions And driving the connecting rod device to drive the first connecting box and the second connecting box to slide along the elastic piece toward the central axis or respectively to slide the two ends of the elastic piece to change the effective length of the elastic piece To adjust the rigidity of the output shaft. The differential drive active variable rigid elastic system of claim 1, further comprising a first sliding table and a second sliding table, wherein the first sliding table and the second sliding table are disposed in parallel One side of a worm wheel. The differential drive active variable rigidity elastic system according to claim 2, further comprising a first sliding member guide post and a second sliding member guiding column, the first sliding member guiding column and The second slider guide column is slidably disposed on the first sliding table and the second sliding table. The differential drive active variable rigid elastic system of claim 3, further comprising a third sliding table and a fourth sliding table, wherein the third sliding table and the fourth sliding table are disposed in the second The worm gear corresponds to one side of the first worm gear. The differential drive active variable rigidity elastic system according to claim 4, further comprising a third sliding member guiding column and a fourth sliding member guiding column, the third sliding member guiding column and the fourth sliding member The guide columns are slidably disposed on the third sliding table and the fourth sliding table, respectively. The differential drive active variable rigid elastic system according to claim 5, wherein the link device comprises a first link set and a second link set, the first link set and the second The connecting rod set is coupled to the first worm wheel, the second worm wheel, the first adapter box and the second adapter box. The differential drive active variable rigid elastic system of claim 6, wherein the first link set comprises a first link and a second link, and the first end of the first link One side is pivotally disposed on one side of the first end of the second connecting rod, and the other side is pivotally disposed on the first sliding member guide post, and the second end of the first connecting rod is pivotally disposed on the first connecting box; The other end of the first end of the second connecting rod is pivotally disposed on the third sliding member guide post, and the second end of the second connecting rod is pivotally disposed on the second connecting box. The differential drive active variable rigid elastic system of claim 7, wherein the second link set comprises a third link and a fourth link, and the first end of the third link One side is pivotally disposed on the first end of the fourth link, and the other side is pivotally disposed on the second sliding member guide post, and the second end of the third connecting rod is pivotally disposed on the second connecting box; The other end of the first end of the connecting rod is pivotally disposed on the fourth sliding member guide post. The second end of the fourth link is pivoted to the first junction box. The differential drive active variable rigid elastic system of claim 8, wherein the first adapter box and the second adapter box respectively comprise at least one roller, and the roller is disposed in the first adapter box and the first Between the two connection boxes and the elastic piece. The differential drive active variable rigidity elastic system according to claim 1 or 9, wherein the first worm wheel and the second worm gear are respectively combined by the same two sub-worm wheels, and two sub-worm wheels The worm gear teeth are interlaced to eliminate the backlash of the first worm wheel and the second worm wheel. A method for actively adjusting the rigidity of an output shaft of an elastic system comprises the steps of: providing a central shaft and connecting the central shaft to a first worm wheel and a second worm wheel; providing an output shaft and disposed on the central shaft An output adjusting end, the rigid adjusting device comprises at least one elastic piece, a first connecting box and a second connecting box, the center of the elastic piece is fixed on the central axis between the two worm wheels, The first connecting box and the second connecting box are slidably sleeved on opposite ends of the elastic piece; a connecting rod device is provided to connect the connecting rod device to the first worm wheel, the second worm wheel, the first a connecting box and the second connecting box; driving the first worm wheel and the second worm wheel to rotate in the same direction to drive the central shaft to drive the output shaft to rotate; and driving the first worm wheel and the second worm wheel Rotating in the opposite direction to drive the connecting rod device to drive the first connecting box and the second connecting box along the elastic piece simultaneously The central shaft slides or slides toward both ends of the elastic piece to change the effective length of the elastic piece to adjust the rigidity of the output shaft. The method for actively adjusting the output shaft rigidity of the elastic system according to claim 11, further comprising a first sliding table and a second sliding table, wherein the first sliding table and the second sliding table are disposed in parallel One side of the first worm wheel. The method for actively adjusting the output shaft rigidity of the elastic system according to claim 12, further comprising a first slider guide post and a second slider guide post, the first slider guide post and the first The two slider guide columns are slidably disposed on the first sliding table and the second sliding table, respectively. The method for actively adjusting the output shaft rigidity of the elastic system according to claim 13 further includes a third sliding table and a fourth sliding table, wherein the third sliding table and the fourth sliding table are disposed on the The second worm gear corresponds to one side of the first worm wheel. The method for actively adjusting the output shaft rigidity of the elastic system as described in claim 14 further includes a third slider guide post and a fourth slider guide post, the third slider guide post and the fourth The slider guide columns are slidably disposed on the third sliding table and the fourth sliding table, respectively. The method for actively adjusting the output shaft rigidity of the elastic system according to claim 15, wherein the link device comprises a first link set and a second link set, the first link set and the The second link set is coupled to the first worm wheel, the second worm wheel, the first adapter box, and the second adapter box. The method for actively adjusting the output shaft rigidity of the elastic system according to claim 16 , wherein the first link set comprises a first link and a second link, and the first link is first One end of the end is pivotally disposed at one of the first ends of the second link The other side is pivotally disposed on the first sliding member guide post, the second end of the first connecting rod is pivotally disposed on the first connecting box; the other end of the first end of the second connecting rod is pivoted The second end of the second connecting rod is pivotally disposed on the second connecting box. The method for actively adjusting the output shaft rigidity of the elastic system according to claim 17, wherein the second link set includes a third link and a fourth link, and the third link is first One end of the end is pivotally disposed on the first end of the fourth link, and the other side is pivotally disposed on the second sliding member guide post, and the second end of the third connecting rod is pivotally disposed on the second connecting box; The other end of the first end of the fourth connecting rod is pivotally disposed on the fourth sliding member guide post, and the second end of the fourth connecting rod is pivotally disposed on the first connecting box. The method for actively adjusting the rigidity of the output shaft of the elastic system, as described in claim 18, wherein the first adapter box and the second adapter box respectively comprise at least one roller, and the roller is disposed in the first junction box and The second adapter box is between the elastic sheet. The method for actively adjusting the output shaft rigidity of the elastic system according to claim 11 or 19, wherein the first worm wheel and the second worm gear are respectively composed of the same two sub-worm wheels, two The worm gears of the sub-worm wheel are interlaced to eliminate the backlash of the first worm wheel and the second worm wheel. A differential drive active variable stiffness elastic system comprising: a central shaft; a first worm gear coupled to the central shaft; a second worm gear coupled to the first worm gear through the central shaft; an output shaft Provided at one of the output ends of the central axis; A rigid adjusting device comprises a plurality of elastic pieces and a plurality of connecting boxes corresponding to the respective elastic pieces, one end of each of the elastic pieces is fixed on the central axis between the two worm wheels, and each of the connecting boxes is slidably Separatingly disposed at the other end of each of the corresponding elastic pieces; and a link device coupled to the first worm wheel, the second worm wheel, and each of the adapter boxes; wherein, the first worm wheel and the second worm wheel When rotating in the same direction, the central shaft is driven to drive the output shaft to rotate; and when the first worm wheel and the second worm wheel are rotated in the opposite direction, the connecting rod device is driven to drive each of the connecting boxes while along the respective The elastic piece slides toward the central axis or slides away from the central axis, so that the effective length of each of the elastic pieces is changed to adjust the rigidity of the output shaft. A human external bone is carried in the human body to assist the human body action. The human external skeletal system comprises a differential drive active variable rigid elastic system and a power supply, and the differential drive active variable rigid elastic system is as claimed. Said in any one of items 1 to 10 and item 21.