CN102537206A - Gravity compensation device - Google Patents

Abstract

The invention relates to a gravity compensation device, which comprises a force output device, a shaft, and an arm rotating with the shaft as a center, wherein when the rotating arm contacts the force output device, an acting force is provided for the contact position of arm by using the force output device such as a torsion spring; and when the arm rotates with the shaft as the center in a first or second quadrant, the contact position of the arm on the force output device persistently changes, thus the force output device presents nonlinear movement relatively to the rotation of the arm. According to the influences of variations of the force arm, relative rotation speed and stress angle on the moment of the shaft, the gravity compensation device can utilize the linear force output device to imitate moment output approximate to a sine function with 0-90 degrees by proper design.

Description

Gravity-compensated device

Technical field

The present invention is a gravity-compensated device, when especially referring to a kind of can in first or second quadrant, the rotation one, relative compensating torque is provided, and with the axle is being center when doing rotation to offset an object, and gravity is to influence that object produced.

Background technique

Among dissimilar equipment; If will the object with a quality be moved or rotates; It is favourable that object is carried out gravity compensation, can offset all or partly the compensation device of gravity is down auxiliary by one, just can less power moves or rotates this object; This with do not have to have saved many energy under the situation of gravity-compensated device.On structure Design, because of power that only must be less just can drive this object, required power plant or double-action mechanism are simple relatively, with regard to cost, also can reduce synchronously.

As shown in Figure 1, for showing a kind of existing gravitational compensation method.Object 11 has a quality W, can be that the center rotates with axle 12, and this object 11 is L with the centre distance of axle 12.Gravity compensation mechanism is meant a torsion spring 13 that is installed on axle 12 centers; One fixing rod 131 of this torsion spring 13 is to be fixed; 132 of movement rods and object 11 rotate synchronously, the influence that gravity is caused when utilizing this torsion spring 13 to remedy or offset this object 11 by 0～90 degree rotation.The spring torque constant of this torsion spring is K _Mθ is the angle of swing of object.According to mathematical formulae

Moment=W*L*Sin the θ of axle 12

The compensation torque of torsion spring 13 is=K _M* θ

Wherein this W, L are constant; Sin θ is the curve of non-linear increasing; Event is along with the moment of the variation gained at θ angle is a non-linear increasing; And this torsion spring 13 is a Hookean spring, and the compensation torque that is provided is a linear increment, so the moment variations that the gravitational compensation method of class can't fully satisfy gravity to be caused.

Be head it off, like U. S. Patent the 6th, 899; " Passive gravity-compensatongmechanisems " patent case of No. 308; Utilize two groups of rotating machinerys, cooperate two groups of springs to be connected, reach the purpose of gravity compensation with the member of aforementioned mechanism with a non-circular surfaces.This structure is on making, and preferred embodiment is to do collocation with a pair of noncircular gear, and the degree of difficulty and the cost of manufacturing are higher, and when the product miniaturization, is considering that foregoing problems is more obvious under the factors such as the strength of materials (metal gear) and collocation precision.

Like U. S. Patent the 7th, 677, No. 523 " Gravity compensation device " then provides another kind of structure in addition.The part of this structural disadvantages for can't emulation trigonometric function slope reducing gradually; Because of if in the pulley radius when contracting its reelability cable can't contact the part that contracts in this; Can be withstood by the outstanding relatively part of leading portion; And the relative distance of loading and power output unit can change with the pulley radius change in rotation process, perhaps as distance when constant application of force angle then can change.

In view of this, when the inventor does rotation in order to solve an existing object with one center,, also designed a kind of gravity-compensated device because of the influence that gravity caused.

Summary of the invention

The present invention is a kind of gravity-compensated device, mainly is the whereabouts that is used for axle, can compensate or offset the object influence that gravity caused when rotated that is connected in axle, just can drive this rotation and can change with less power.

For reaching above-mentioned purpose; Gravity-compensated device of the present invention comprises that a power output unit, one and one are the arm that rotation is done at the center with the axle; Mainly be when the arm of rotation contacts with the power output unit; Use as the power output unit of torsion spring provides the contact position of this arm of active force, arm be the center with the axle first or two quadrant in the rotating process, the contact position of this arm on this power output unit can continue change; And make capable output unit in relative rotation the loading angle of speed, the arm of force that acts on this arm and arm change thereupon; By suitable design, just can make this according to the increasing progressively of angle of swing, it is one non-linear and be similar to the curve that increases progressively of sine function 0～90 degree that the moment values that is produced demonstrates.

Wherein, the start scope of this arm is in first and second quadrant.

Moreover gravity-compensated device of the present invention includes a casing in addition, and this power output unit, axle and arm all are arranged in the casing; This meeting is by extending out in the casing, and this power output unit includes a shifting part and a torsion spring, and the center of this torsion spring is arranged on the shifting part; This shifting part can draw this torsion spring; Make the angle of swing of shifting part identical with the windup-degree of torsion spring, this shifting part is centered close in the rotate path of arm, when this arm rotation; One contact of this arm can contact with this shifting part and make it turn; The contact place that this torsion spring then provides an active force to bestow arm by shifting part, along with the lasting rotation of axle, the contact position of the contact of this arm on shifting part also can change.

In the gravity-compensated device of the present invention; The wall place of this casing is provided with an adjustment screw in addition; This torsion spring includes a helix district and reaches by a helix district extended fixing rod of institute and a movement rod; The end that this adjustment screw extends in the casing is to be positioned at this spiral winding, when this adjustment screw means, can change the active line number of turns of this torsion spring.

In the gravity-compensated device of the present invention; This casing another side wall place has a positional lock firmware; This positional lock firmware can change it in the position at wall place through adjustment; Wherein this power output unit is a torsion spring, and this torsion spring includes a helix district and by an extended fixing rod of helix district institute and a movement rod, and this positional lock firmware is also being fixed the position of the fixing rod of this torsion spring.

In the gravity-compensated device of the present invention; This power output unit is a torsion spring; This torsion spring includes a helix district and by an extended fixing rod of helix district institute and a movement rod, the position of this fixing rod is fixed, and this arm is to be to contact with movement rod with contact.

In the gravity-compensated device of the present invention; This power output unit, axle and arm are to be arranged in the support; This support has the containing space that is open; The position of this power output unit and axle all is fixed in the space of support, also can rotate with the axle center when arm extends to the external world, and the contact of this arm contact position on the power output unit when rotated also can change.

Design according to the present invention; This power output unit can be a torsion spring; Be provided with a support in addition and supply this axle and torsion spring setting, this torsion spring includes a helix district and by this a line district extended fixing rod of institute and a movement rod, wherein fixing rod is fixed in this support; Movement rod then contacts with a contact of this arm; The contact position of this contact on movement rod can change along with this arm rotation, forms a gravity-compensated device by this, and wherein this arm can directly connect the object place that desire is rotated.

Now the detailed description and the claim that cooperate following diagram, embodiment, will on address this creation other purpose and advantage be specified in after.

Description of drawings

Fig. 1 is the schematic representation of existing gravity-compensated device;

Fig. 2 is the schematic representation of the embodiment of the invention;

Fig. 3 is the figure of mathematics calculation of the present invention;

Fig. 4 simulates the plotted curve () of the moment and the angle (θ 1) of actuator state for the present invention;

Fig. 5 simulates the plotted curve (two) of the moment and the angle (θ 1) of actuator state for the present invention;

Fig. 6 is the analysis chart of moment and angle;

Fig. 7 applies to first embodiment's at product place stereogram for the present invention;

Fig. 8 applies to first embodiment's at product place exploded view for the present invention;

Fig. 9 is the illustrative view of first embodiment of the invention;

Figure 10 is the stereogram of another angle of first embodiment of the invention;

Figure 11 is that reality of the present invention is in second embodiment's at product place stereogram;

Figure 12 is that reality of the present invention is in second embodiment's at product place exploded view;

Figure 13 A is general torsion spring when utilization is of the present invention, the angle of swing schematic representation of axle;

Figure 13 B is that desirable torsion spring device applies to the present invention, the angle of swing schematic representation of axle.

[primary clustering symbol description]

11 objects

12

13 torsion springs

131 fixing rods

132 movement rods

The 2A gravity-compensated device

23 power output units

24

23 arms

231 contacts

The F active force

30 points

31 points

32 points

35 arching trajectorys

41 curves

42 curves

50 casings

501 lids

502 containers

503 axis holes

504 helical holes

505 curve baths

51 power output units

511 torsion springs

5111 helix districts

5112 fixing rods

5113 movement rods

512 shifting parts

5121 center-poles

5122 surface of contact

5123 Ju pieces

5124 center-poles

52

53 arms

531 contacts

55 adjustment screws

551 blind holes

56 positional lock firmwares

561 holders

562 screws

563 attachment holes

564 screws

The 9A gravity-compensated device

90 supports

901 central shafts

902 draw-in grooves

903 axis holes

91 torsion springs

911 helix districts

912 fixing rods

913 movement rods

92

93 arms

Embodiment

As shown in Figure 1, be the schematic representation of the basic model of gravity-compensated device of the present invention.This gravity-compensated device 2A includes a power output unit 21, one spool 22 and can be the arm 23 that rotation is done at the center with axle 22.The rotating range of this arm 23 is limited in this example in the first quartile, on this arm 23, has a contact 231, and this contact 231 is being kept fixed range apart from these axle 22 centers.This power output unit 21 is centered close in the rotate path of arm 23, and this arm 23 contacts with power output unit 21 with contact 231 when rotated, and along with the difference of angle of swing, the contact position of this contact 231 on power output unit 21 will continue to change.This power output unit 21 must be able to produce a directed force F in contact 21 contacts with it, and along with the increase of angle of swing, directed force F also must increase synchronously.Therefore this power output unit 21 includes a torsion spring in the present embodiment, and the center of this torsion spring must be positioned at the rotating center with the power output unit, and the power output unit is only illustrated with sketch in this figure, detailed structure and graphic will in after remake explanation.But not as limit, this power output unit also can use other Hookean spring, like extension spring etc.By this when these arm 23 rotations; The contact position of this arm 23 on this power output unit 21 will continue to change; And make capable output unit 21 in relative rotation the loading angle of speed, the arm of force that acts on this arm 23 and contact 231 also change thereupon; Via the present invention suitable calculating and design, just can make this according to the increasing progressively of angle of swing, it is one non-linear and be similar to the curve that increases progressively of sine function 0～90 degree that the moment values that is produced appears.But therefore do not exceed, the user also can optionally be designed to the kenel of other different non-linear increasing.

As shown in Figure 3, be principle explanation sketch of the present invention.Point 30 is the central point of axle; Point 31 is the central point of power output unit; This arm moves in first quartile with respect to axle, and the point of contact on this arm and the power output unit is represented with the stain of periphery, along with the arm angle of swing is different; The stain position is also different, and this arc curve 35 is promptly represented the track of stain process.Contact on this arm and axle center stationary phase are apart from being R, and this contact Driving force output unit makes this power output unit make the angular turn of hatched example areas.Foundation when realization of the present invention is based on following three factors as design:

1. the power output unit had rotated θ 2 when this arm rotated θ 1 with respect to axle, and this θ 1 is a non-linear relation with θ 2;

Point of contact on this arm and the power output unit apart from power output unit center apart from r then with the different variations that have length of angle;

3. each point of contact on the power output unit, the active force of power output unit can with the different angle of arm generation.

According to above-mentioned factor, the moment at axle of the present invention place is output as:

The power output unit is in moment * (R/r) the * Cos (active force of power output unit and the angle of arm) of this relative position output

According to above-mentioned explanation, the present invention further provides relevant mathematics calculation formula.Brought forward is said, and this point 30 is the central point of axle, and point 31 is the central position of power output unit.Point 31 with respect to point 30 relative positions be (d, h).Point 32, θ ' and r ' use for the aid illustration formula.K is the spring torque constant.

Mathematics calculation formula is following:

$R*\sin \mathrm{\θ}1=r^{\′}*\mathrm{Sin}{\mathrm{\θ}}^{\′}\→r^{\′}=\frac{R*\sin \mathrm{\θ}1}{{\mathrm{Sin\θ}}^{\′}}$

$\frac{R*\mathrm{Cos\θ}1-h}{R*\mathrm{Sin\θ}1}=\mathrm{Cot}{\mathrm{\θ}}^{\′}\→{\mathrm{\θ}}^{\′}={\tan }^{-1}\frac{R*\mathrm{Sin\θ}1}{R*\mathrm{Cos\θ}1-h}$

$r^{\′}*{\cos \mathrm{\θ}}^{\′}=r*\cos (\mathrm{\θ}2-{\tan }^{-1}\frac{d}{R-h})\→r=\frac{r^{\′}\cos {\mathrm{\θ}}^{\′}}{\cos (\mathrm{\θ}2-{\tan }^{-1}\frac{d}{R-h})}$

$\frac{r^{\′}*{\sin \mathrm{\θ}}^{\′}\·d}{r^{\′}*\cos {\mathrm{\θ}}^{\′}}=\tan (\mathrm{\θ}2-t{\mathrm{an}}^{-1}\frac{d}{R-h})\→\mathrm{\θ}2={\tan }^{-1}\frac{r^{\′}*{\sin \mathrm{\θ}}^{\′}-d}{r^{\′}*\cos {\mathrm{\θ}}^{\′}}+{\tan }^{-1}\frac{d}{R-h}$

$\mathrm{Angle\; between\; R\; and\; r}=(\mathrm{\θ}2-\mathrm{\θ}1-\mathrm{ta}{n}^{-1}\frac{d}{R-h})$

$\mathrm{torque}=k*\mathrm{\θ}2*R/r*\cos (\mathrm{\θ}2-\mathrm{\θ}1-{\tan }^{-1}\frac{d}{R-h})$

Therefore, as long as set R, h, the d value can be obtained corresponding θ 2 of arbitrary θ 1 value and r value according to above-mentioned formula, also can calculate the output torque of the present invention in this angle.

Like Fig. 4 and shown in Figure 5, simulate plotted curve () and (two) of moment and the angle (θ 1) of actuator state for the present invention, in Fig. 4; This R value is set at 20; D=0, when h cumulative by 0 to 19 several moments (T) curves of being appeared, by knowing among the figure; When h was cumulative, M curve can be by going up skew left to the bottom right.In Fig. 5, this R value is set at 20, h=0, when d cumulative by 0 to 19 several moments (T) curves of being appeared, by knowing among the figure, when d is cumulative, M curve will by under the left side to upper right skew.On this basis down, when desire of acquisition was made the actual M curve of object of gravity compensation, the inventor can set out the R value according to the size of gravity-compensated device; Suppose an approaching h and d value afterwards earlier; After obtaining a hypothesis M curve after calculating according to formula, the difference of comparison and actual M curve is again according to the logic of Fig. 4 and Fig. 5; In good time increase and decrease h or d value, last R, h and the d value that just can obtain the gravity-compensated device of the present invention of closing to reality M curve.

As shown in Figure 6, be object when rotation and the moment of apparatus of the present invention and the comparison sheet of angle.This figure is promptly according to aforesaid calculation mode; Obtain the preferred values of apparatus of the present invention related data, R=25mm wherein, h=7.1375mm; D=3.3125mm; And both moments when 90 spend are set at 1 unit make comparisons, curve among the figure 41 increases progressively curve for object by the moment that plumbness rotates to level, receives the moment that influences of gravity to present nonlinear increasing progressively.And curve 42 increases progressively curve for the moment according to the gravity-compensated device of the present invention of above-mentioned formula gained; Can find that by figure two curvilinear paths are close; So the present invention is installed on rotating shaft place of an object; Just ability target compensation gravity effect when rotated can drive this object and use instead once less drive unit.

Practice of the present invention with that is the embodiment in the product place explain; In the following example; The present invention utilizes torsion spring as the power output unit; But the diameter of torsion spring can have influence on its angle of swing, and the present invention explains with regard to each embodiment's structure earlier, just influences situation again and does a discussion and an explanation.

Like Fig. 7, shown in 8, use principle of the present invention to implement the stereogram and the exploded view of illustration in first of product place.It includes a casing 50, a power output unit 51,52 and one arm 53 gravity-compensated device 5A of the present invention.This casing 50 is by the formed hollow box in lid 501 and one container, 502 involutory backs, in order to ccontaining aforementioned components.Have an axis hole 503 on this lid 501, supply this axle 52 to extend out.These axle 52 places are connecting this arm 53, and these arm 53 places have a contact 531, and this contact 531 is being kept a fixed range apart from these axle 52 centers.This power output unit 51 includes a torsion spring 511 and a shifting part 512.This torsion spring 511 includes a helix district 5111 and reaches an extended fixing rod 5112 in place and a movement rod 5113 thus.This shifting part 512 has a center-pole 5121; This center-pole 5121 is fixed in the casing 50; Make shifting part 512 can do the rotation of wide-angle for the center according to center-pole 5121; These arm 53 places and the guide groove 532 with an arc pass through for center-pole 5121, and make center-pole 5121 not interfere the rotation of arm 53.And the toggle member 512 has a curved contact surface 5122 and an Ju member 5123, the contact surface parts 5122 and 5123 Ju 5121 from a distance from the center bar.Contact surface 5122 which is intended for contact with the contact member 531, and the Ju member 5123 for fastening the torsion spring 511 to the travel bar 5113, and the position of the fixed arm 5112 is fixed to the housing 50 of .

As shown in Figure 9; When this axle 52 when rotated; This arm 53 produces synchronous rotation; This shifting part 512 is buckled in movement rod 5,113 one sides of torsion spring 511 because of its fastener 5123, and when arm 53 contacted with the surface of contact 5122 of this shifting part 512 with this contact 531, the torsion that torsion spring 5111 produces because of reversing can offer contact 531 positions of shifting part 512 1 active forces in this arm 53; Increasing along with axle 52 angle of swing; The contact position of this contact 531 on surface of contact 5122 continue to change, and this power output unit 51 loading angle of speed, the arm of force that acts on this arm 53 and contact 531 in relative rotation also changes thereupon, and makes the moment of axle 52 present the pattern of a non-linear increasing.

Hope to have the effect of a fine setting when satisfying actual assembled at the foregoing description, proofread and correct or adjustment axle 52 last moment output modes that produce for the user.Like Fig. 8 and shown in Figure 10, in this gravity-compensated device 5A, include an adjustment screw 55 and a positional lock firmware 56 in addition.The wall place of the container 502 of this casing 50 has a screw hole 504; This place is the part that is provided with of adjustment screw 55; This adjustment screw 55 has a blind hole 551; This blind hole 551 is to supply the less center-pole of this another root diameter of shifting part 512 relative center-poles 5121 positions 5124 to be provided with wherein, and the external diameter of this adjustment screw 55 equals or be slightly larger than the internal diameter in the helix district 5111 of this torsion spring 511, when adjustment screw 55 is locked helix district 5111, can change the active line number of turns of this torsion spring 511; The spring torque constant also can change, and this also can change this moment values of 52.And this positional lock firmware 56 comprises a holder 561 and a screw 562; The wall place of this container 502 is then forming a curve bath 505; These holder 561 places have an attachment hole 563; Fixing rod 5112 for this torsion spring 511 is inserted in this attachment hole 563, and holder 561 has a screw 564, is locked in screw 564 places by the outside through this curve bath 505 for this screw 562; Can the fixing rod 5112 of torsion spring 5111 be fixed in the inwall of container 502 by this with different amount; Because adjustment screw 55 external diameters are slightly larger than the internal diameter in the helix district 5111 of torsion spring 511, the action of locking (or release) can change torsion spring 511 open angles, and the space of an adjustment so can be provided.

Like Figure 11 and shown in Figure 12, for the present invention applies to stereogram and the exploded view that second of product place implements illustration.Gravity-compensated device 9A of the present invention is made up of a support 90, a power output unit, 93 on 92 and one arm.This power output unit is a torsion spring 91, and this torsion spring 91 includes a helix district 911 and reaches by 911 extended fixing rods 912 in helix district and a movement rod 913.This support 90 has the containing space that is open; Aforementioned components then is provided with wherein; This support 90 has a central shaft 901, is inserted in 911 centers, helix district of this torsion spring 91, with the position of fixing this torsion spring 91; Central shaft 901 belows have a draw-in groove 902 in addition in support 90, use for fixing rod 912 and be inserted in this and fixing its position.Have one group in this support 90 in addition and be the axis hole 903 that is oppositely arranged, be provided with wherein for this axle 92.This axis hole 903 is not in same center line with central shaft 901, and in fact the central point of this central shaft 901 is on the mobile route of arm 93 rotations.These arm 93 places have a contact 931 in addition, and this contact 931 has a fixed range apart from axle 52 centers, and this arm 93 this contact 931 when rotated is to keep contacting with movement rod 913, and drive this movement rod 913 rotations.This contact 931 can change according to the angle of arm 93 rotations and change thereupon with the contact position of movement rod 913.

The embodiment of Figure 11 and Figure 12 is that a kind of structure comparatively simply designs; The moment of the axle 52 of this gravity-compensated device 5A still appears non-linear cumulative with the angle of swing increase; In the present embodiment; Only be applicable to the enough little h of torsion spring diameter, when d is enough big, under the influence that the torsion spring diameter of ignoring causes, could be suitable for.This arm 53 can be directly connected in the object place of desire rotation among this embodiment, but not object and axle 52 are connected.

In above-mentioned two embodiments; Mainly be to utilize the primary clustering of torsion spring as the power output unit; But when using the diameter that need consider torsion spring when exerted oneself in the unit in the torsion spring conduct, when in fact directly using torsion spring, its fulcrum can move and can influence its rotation angle; Shown in Figure 13 A, Figure 13 B; Figure 13 A is a torsion spring, and Figure 13 B is a desirable torsion spring device, utilizes structure of the present invention from same angle; The schematic representation that two torsion springs turn 90 degrees separately can find out that angle [alpha] and α 1 that output shaft rotates are obviously different, torsion spring feedback strength to the angle of swing of arm be affected and Figure 13 B in the center of rotation of torsion spring be along with its circumference moves.Therefore in the first embodiment of the invention; Be to constitute one group of power output unit by a shifting part and a torsion spring; Utilize a shifting part torsion spring center to be coincided with a movement rod of its axle center and permanent twist spring; This merging device can be regarded as a desirable torsion spring, the center of rotation of shifting part can not change and the torsion spring rotation angle consistent with shifting part.

Comprehensive the above; The present invention utilizes a power output unit (like torsion spring) to provide an active force in the arm place that contacts with it; But during with the rotation of this arm of person, the contact position of arm and power output unit also continues change, so can let the power output unit in relative rotation the loading angle of speed, the arm of force that acts on this arm and arm change thereupon; Make the axle that is connected in arm can produce non-linear cumulative moment, make single unit system can offset an actual object influence that gravity caused when rotated.

The above person is merely in order to explain the present invention's preferred embodiment; Be not that attempt is done any formal restriction to the present invention according to this; Be with, all have in following any modification or change of doing relevant the present invention of identical invention spirit, all must be included in the category that the invention is intended to protection.

Claims (7)

1. gravity-compensated device; It is characterized in that; Include a power output unit, one and can be the arm that rotation is done at the center with the axle, have a contact apart from an axle center fixation distance on this arm, this power output unit be centered close in the rotate path of arm; When this arm rotation, can contact with the power output unit with this contact; This power output unit provides an active force in the contact position of arm, and along with the lasting rotation of axle, and contact position and the loading angle of this contact of the contact of this arm on this power output unit also can change.

2. gravity-compensated device as claimed in claim 1 is characterized in that, the start scope of this arm is in first and second quadrant.

3. gravity-compensated device as claimed in claim 1 is characterized in that other includes a casing; This power output unit, axle and arm all are arranged in the casing, and this meeting is by extending out in the casing, and this power output unit includes a shifting part and a torsion spring; The center of this torsion spring is arranged on the shifting part, and this shifting part can draw this torsion spring, makes the angle of swing of shifting part identical with the windup-degree of torsion spring; This shifting part is centered close in the rotate path of arm; When this arm rotation, the contact of this arm can contact and make it turn with this shifting part, and this torsion spring then provides an active force to be bestowed the contact place of arm by shifting part; Along with the lasting rotation of axle, the contact position of the contact of this arm on shifting part also can change.

4. gravity-compensated device as claimed in claim 3; It is characterized in that; The wall place of this casing is provided with an adjustment screw in addition, and this torsion spring includes a helix district and by a helix district extended fixing rod of institute and a movement rod, the end that this adjustment screw extends in the casing is to be positioned at this spiral winding; When this adjustment screw means, can change the active line number of turns of this torsion spring.

5. gravity-compensated device as claimed in claim 3; It is characterized in that; This casing another side wall place has a positional lock firmware, and this positional lock firmware can change it in the position at wall place through adjustment, and wherein this power output unit is a torsion spring; This torsion spring includes a helix district and by an extended fixing rod of helix district institute and a movement rod, and this positional lock firmware is also being fixed the position of the fixing rod of this torsion spring.

6. gravity-compensated device as claimed in claim 1; It is characterized in that; This power output unit is a torsion spring; This torsion spring includes a helix district and by an extended fixing rod of helix district institute and a movement rod, the position of this fixing rod is fixed, and this arm is to be to contact with movement rod with contact.

7. gravity-compensated device as claimed in claim 1; It is characterized in that; This power output unit, axle and arm are to be arranged in the support, and this support has the containing space that is open, and the position of this power output unit and axle all is fixed in the space of support; Also can rotate with the axle center when arm extends to the external world, the contact of this arm contact position on the power output unit when rotated also can change.

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