CN103192406A - Robot joint driver with variable rigidity - Google Patents

Abstract

The invention provides a robot joint driver with variable rigidity and relates to joint rigidity adjustment by utilizing a flexible rack mechanism. The flexible rack mechanism is connected between the output end of a rigid speed reducer and a joint connecting rod in series. A pair of rigidity adjusting mechanisms is anti-symmetrically arranged along the axial direction of a flexible rack, and accordingly forward and reverse joints are adjustable. Displacement of a gear relative to the flexible rack is solely confirmed through a turn angle of a rigidity adjusting motor by utilizing the flexible rack mechanism, accordingly a joint rigidity value is confirmed solely, and joint rigidity adjustment can be achieved by controlling the turn angle of the rigidity adjusting motor. The robot joint driver adopts the flexible rack mechanism, integrates an elastic link and the rigidity adjusting mechanisms and is short in adjusting time and compact in structure.

Description

A kind of joint of robot driver of stiffness variable

Technical field

The present invention relates to a kind of joint of robot driver of stiffness variable, relate in particular to the stiffness variable joint of robot driver that adopts the metal flexible tooth bar.The metal flexible tooth bar plays the double action of elastic link and joint stiffness governor motion in joint driver.

Background technology

The distinct issues in current robot field are exactly how to improve the adaptability of robot.Passive flexibility and active force control are to improve the adaptive two kinds of comparatively common methods of robot.Typical passive flexible case is indirect center compliance RCC (Remote Center Compliance), but its flexibility is difficult to carry out ACTIVE CONTROL, and application surface is narrower.Active force control needs outside high-precision force sensor; Require high to the precision of sensor, the bandwidth of sample frequency and the real-time of control algolithm; Under non-structure environment, be difficult to guarantee security, and robustness is lower.Joint driver under the active force control needs consumed energy always, can not store or release energy, and application limitation is big.

The joint of robot driver of stiffness variable can be regulated joint stiffness in real time according to the task needs, improves the adaptability of robot under non-structure environment.Its major technique feature is: the adjustable elastic link of serial or parallel connection rigidity on driving-chain can transform kinetic energy and the elastic potential energy in joint mutually.The main application fields that becomes the rigidity joint driver is divided into two classes: the intrinsic dynamics of man-machine interaction and Adjustment System.Become the rigidity joint driver for solve robot of new generation man-machine safe, improve dynamic characteristic and save key issues such as energy significant.

Mechanical type change rigidity joint driver is the most common, and its version is versatile and flexible, uses face width.Mechanical type becomes that the rigidity joint driver generally can be divided into the antagonism formula, changes structural formula, mechanical conditioning type and hybrid etc. 4 kinds.The weak point that existing change rigidity joint driver mainly exists is: elastic link and governor motion are independent separately.In order to satisfy the requirement of joint of robot rigidity nonlinear change, can adopt nonlinear spring or " Hookean spring+non-linear governor motion " to realize usually.From the theory of mechanisms angle, if elastic link and governor motion can be united two into one, can simplify mechanical mechanism and promote the adaptability that becomes the rigidity joint.

Becoming the possible application of rigidity joint driver comprises: the human-computer interaction security of hoisting machine people under family's service environment increases sense of experience of users and comfort; Apply the joint rehabilitation exercise that becomes rigidity at patient's joint, if patient twitches, can absorb impact, avoid injuring human body; Avoid machine human and environment generation rigid collision, protection robot and expensive peripheral equipment; Regulate the intrinsic frequency of joint of robot, save the energy resource consumption in jump/walking/running action.According to modularization idea, a plurality of change rigidity joint drivers are assembled into robot.This novel machine people can be widely used in home services, gait rehabilitation, wearable robot, walk/fields such as running robot.Become the rigidity joint driver can the hoisting machine people to the adaptability of environment with enlarge the application of robot, have broad application prospect.

Summary of the invention

The purpose of this invention is to provide a kind of stiffness variable joint of robot driver that is applicable to the man-machine coordination operation, be intended to the difficult problem that bumps at the machine human and environment, especially carry out work compound at the machine person to person, according to the rigidity of task needs real time altering joint of robot.When robot carries out the precision operation, increase the rigidity of joint driver, guarantee location and path accuracy; When robot contacts with human body, reduce the rigidity that the joint drives, guarantee that human body preserves from.

According to an aspect of the present invention, provide a kind of joint of robot driver of stiffness variable, it is characterized in that comprising: the joint drive motors; Rigidity is regulated parts; Output, it is connected mutually with the joint of robot connecting rod; The rigidity deceleration component is used for regulating the equilbrium position of output under the different loads effect.

Description of drawings

Below in conjunction with accompanying drawing technical solution of the present invention is described further:

Figure 1A is the structure chart of the joint of robot driver of stiffness variable according to an embodiment of the invention;

Figure 1B is the structure chart of the main driving-chain of the rigidity governor motion among Figure 1A.

Fig. 1 C is the antisymmetry layout of the rigidity governor motion among Figure 1A.

Fig. 1 D has shown the structure chart of the flexible rack that adopts among Figure 1B.

Fig. 2 A and 2B are used for the explanation joint stiffness and regulate the parameters relationship that the relation between the displacement relates to.

The specific embodiment

Below in conjunction with accompanying drawing embodiments of the invention are described.

A characteristic feature of the joint of robot driver of stiffness variable is: adopt the metal flexible rackwork that elastic link and governor motion are united two into one.The metal flexible tooth bar of between the output of the rigidity decelerator of joint driver and shutdown connecting rod, connecting.This flexible rack itself has certain elasticity, can effectively store and release energy, thereby avoid joint connecting rod and environment instead to give birth to rigid collision; Flexible rack carries gear pair, is convenient to carry out the adjusting of joint stiffness, and compact conformation can increase or reduce joint stiffness fast according to the task needs.

In the man-machine coordination operation process, coming in contact even collide between people and the robot is inevitably, for this reason, how to guarantee that it is vital that impulsive force does not injure human body, and the joint stiffness that reduces robot fast is one of the most feasible solution.When robot carried out accurate localization or TRAJECTORY CONTROL, the user always expected that the joint stiffness of robot is very big, thereby guarantees terminal positioning accuracy, and this just needs to increase fast joint stiffness.Therefore, under the man-machine interaction operating environment, the rigidity of joint of robot regulated in real time being absolutely necessary.

Specifically comprise according to one embodiment of present invention:

(1) frame for movement of flexible rack formula stiffness variable joint driver:

The frame for movement of flexible rack formula stiffness variable joint driver according to an embodiment of the invention comprises joint drive motors 1, rigidity deceleration component, rigidity adjusting parts 5 and output 6 shown in Figure 1A-1D.Joint drive motors 1 adopts commercial servomotor, and output 6 is connected mutually with the joint of robot connecting rod.

The rigidity deceleration component comprises harmonic speed reducer 2, shell (frame) 3, bearing 4, and major function is to regulate the equilbrium position of output 6 under the different loads effect.

Rigidity is regulated parts 5 and is connected with the rigidity deceleration component, comprises gear pair rigidity governor motion 5A and 5B that a flexible rack 13 and a pair are arranged along flexible rack 13 axis antisymmetry.Be the conjugation engagement between flexible rack 13 and the spur gear 9.The rigidity output shaft 7 of the two ends of flexible rack 13 and harmonic speed reducer is connected.Under the no angular deformation situation, the intersect vertical axis of the path of contact of flexible rack 13 and rigidity output shaft 7.

The driving-chain of rigidity governor motion 5 is: rigidity is regulated the axis of motor 12 and the axis normal of rigidity output shaft 7 is arranged, the bevel pinion 11 that drives bevel gear centering rotates; The bevel gear wheel 10 of bevel gear centering is coaxial with spur gear 11, drives spur gear 9(and flexible rack 13 engagements) rotate; Spur gear 9 and flexible rack 13 engagements, flexible rack 13 is fixing with respect to shell 3, moves along flexible rack 13 thereby make rigidity regulate parts 5; Slide block 14 is regulated parts 5 with rigidity and is connected mutually, and matches with square guide rail 15, makes rigidity regulate parts 5 and moves along square guide rail 15; And square guide rail 15 contains cross-bearing 8 with output 6(, and is concentric with bearing 4) be connected mutually, and the intersect vertical axis of the axis of square guide rail 15 and output 6.To sum up, when rigidity is regulated motor 12 runnings, cause that rigidity adjusting parts 5 are with respect to the change of the axial line distance of rigidity output shaft 6.

The rigidity governor motion 5A and the 5B that why use a secondary antisymmetry to arrange are adjustable in order to realize that forward and reverse joint stiffness is.Be the example explanation with rigidity governor motion 5A, regulate in rigidity under the just commentaries on classics driving of motor 12, rigidity is regulated parts 5A to the axis direction motion near output 6, radial load from the corresponding spur gear 9 of loading moment forward or backwards of output 6 increases, cause the amount of deflection that flexible rack 13 is bigger, namely joint stiffness reduces; Regulate in rigidity under the counter-rotating driving of motor 12, two rigidity are regulated parts 5 move toward one another, then rigidity is regulated parts 5A to the axis direction motion away from output 6, radial load from the corresponding spur gear 9 of loading moment forward or backwards of output 6 reduces, cause the amount of deflection that flexible rack 13 is less, namely joint stiffness increases.Further, look flexible rack 13 and be spring beam, amount of deflection is converted the joint angle distortion, joint stiffness K and rigidity adjusting motor 12 displacement σ's is square relevant so, i.e. K=f (σ ²), thereby the non-linear adjusting of realization joint stiffness.Two rigidity governor motions carry out independent control respectively, then just can realize/the oppositely asymmetric adjusting of rigidity.

(2) relation between joint stiffness and the adjusting displacement:

Adopt succinct linear analysis method, set up the statics model that the stiffness variable joint drives.The flexible rack two ends are connected mutually with the rigidity output shaft, can be considered three fixing degree statically indeterminate beams of two ends, shown in Fig. 2 A.Concrete research step is:

1. according to small deformation, linearisation hypothesis, ignore the horizontal support reaction at flexible rack two ends, i.e. F _Ax=0, F _Bx=0;

2. this variable shaped beam is removed superfluous constraint, and replace with corresponding unnecessary branch counter moment, be converted into suitable system, shown in Fig. 2 B;

3. by deformation compatibility condition, the corner that can get the two fixed ends cross section is zero, namely

θ _A=0 （a）

θ _B=0 （b）

According to linear superposition method, can get,

${\mathrm{\&theta;}}_A=-\frac{F_r\mathrm{ab}(l+b)}{6\mathrm{EIl}}+\frac{M_{A}l}{3\mathrm{EI}}+\frac{{\mathrm{<figure-callout\; id="6"\; label="M\; B\; l"\; filenames="HDA00003022823700011.png,HDA00003022823700031.png"\; state="\{\{state\}\}">M</figure-callout>}}_{B}l}{6\mathrm{EI}}---\left(c\right)$

${\mathrm{\&theta;}}_B=\frac{F_r\mathrm{ab}(l+a)}{6\mathrm{EIl}}-\frac{M_{A}l}{6\mathrm{EI}}-\frac{{\mathrm{<figure-callout\; id="3"\; label="M\; B\; l"\; filenames="HDA00003022823700011.png"\; state="\{\{state\}\}">M</figure-callout>}}_{B}l}{3\mathrm{EI}}---\left(d\right)$

With formula (c) with (d) respectively substitution formula (a) with (b), can get two additional equations, namely

$-\frac{F_r\mathrm{ab}(l+b)}{6\mathrm{EIl}}+\frac{M_{A}l}{3\mathrm{EI}}+\frac{{\mathrm{<figure-callout\; id="6"\; label="M\; B\; l"\; filenames="HDA00003022823700011.png,HDA00003022823700031.png"\; state="\{\{state\}\}">M</figure-callout>}}_{B}l}{6\mathrm{EI}}=0---\left(e\right)$

$\frac{F_r\mathrm{ab}(l+a)}{6\mathrm{EIl}}-\frac{M_{A}l}{6\mathrm{EI}}-\frac{{\mathrm{<figure-callout\; id="3"\; label="M\; B\; l"\; filenames="HDA00003022823700011.png"\; state="\{\{state\}\}">M</figure-callout>}}_{B}l}{3\mathrm{EI}}=0---\left(f\right)$

Simultaneous formula (e) and (f) is obtained the branch counter moment of two stiff ends, namely

$M_A=\frac{F_r{\mathrm{ab}}^2}{l^2}---\left(g\right)$

$M_B=\frac{F_r{a}^{2}b}{l^2}---\left(h\right)$

4. obtained the vertical support reaction of two stiff ends by equilibrium equation;

$F_{\mathrm{Ay}}=\frac{F_r{b}^2(l+2a)}{l^3}---\left(i\right)$

$F_{\mathrm{By}}=\frac{F_r{a}^2(l+2b)}{l^3}---\left(j\right)$

5. utilize the deflection formula of principle of stacking and beam, can try to achieve the amount of deflection of flexible rack stress point place flexible rack, that is:

${\mathrm{\&omega;}}_r={\mathrm{\&omega;}}_{F_r}+{\mathrm{\&omega;}}_{M_A}+{\mathrm{\&omega;}}_{M_B}---\left(k\right)$

${\mathrm{\&omega;}}_F=\frac{F_r\mathrm{ab}}{6\mathrm{lEI}}(a^2+b^2-l^2)---\left(l\right)$

${\mathrm{\&omega;}}_{M_A}=\frac{M_{A}a}{6\mathrm{lEI}}(-2l^2-a^2)---\left(m\right)$

${\mathrm{\&omega;}}_{M_B}=\frac{M_{B}a}{6\mathrm{lEI}}(l^2-a^2)---\left(n\right)$

With formula (g), (h), (l), (m) and (n) bring (k) Shi Kede into

${\mathrm{\&omega;}}_r=\frac{F_r\mathrm{ab}}{6\mathrm{lEI}}({2a}^2+b^2-2\mathrm{ab}-\frac{a^3+l^3}{l})---\left(o\right)$

6. utilize triangle formula, derive the output angular deformation amount of amount of deflection correspondence;

$\mathrm{\&delta;}=\frac{{\mathrm{\&omega;}}_r}{a-l/2}---\left(p\right)$

7. joint loading moment

$M=F_r(a-l/2)---\left(q\right)$

8. joint stiffness

$K=\frac{M}{\mathrm{\&delta;}}---\left(r\right)$

Bring formula (r) into formula (o), (p) with (q), then

$K=\frac{6\mathrm{lEI}{(a-l/2)}^2}{\mathrm{ab}({2a}^2+b^2-2\mathrm{ab}-\frac{a^3+l^3}{l})}---\left(s\right)$

Because b=l-a, so

$K=\frac{6{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00003022823700011.png"\; state="\{\{state\}\}">l</figure-callout>}}^2\mathrm{EI}{(a-l/2)}^2}{a{(l-a)}^2(4l-a)}---\left(t\right)$

Further, above-mentioned joint stiffness K is relevant with three factors such as E, I and a, and wherein E is the elastic modelling quantity of the material therefor of flexible rack, is constant.I is the moment of inertia of tooth bar, for a definite tooth bar, is constant.Displacement a is only to be determined joint stiffness K by regulating so.

Further, adopt rack-and-pinion, the corner displacement σ that above-mentioned adjusting displacement a regulates motor by rigidity is only definite, and a is the linear function of σ.Therefore, the corner σ of control rigidity adjusting motor can realize the adjusting of joint stiffness K, i.e. K=f (σ ²).

Outstanding substantive distinguishing features and the obvious improvement of technical solution of the present invention is mainly reflected in:

The stiffness variable shutdown driver that the present invention relates to has adopted the metal flexible tooth bar, relies on the geometrical relationship of rack-and-pinion kinematic pair, is regulated the corner of motor by rigidity and determines that gear is with respect to the adjusting displacement of flexible rack; Flexible rack is set up the statics model, know by inference joint stiffness only with regulate the square relevant of displacement.Thereby regulate non-linear, the adjusting on a large scale that the motor corner is realized joint stiffness by control rigidity.Compared with prior art, flexible rack formula stiffness variable joint driver, the physical dimension compactness, the adjusting time is short, can be widely used in the robot of man-machine interaction operation, produces good practical significance, and economic results in society are remarkable.

Below only be concrete exemplary applications of the present invention, protection scope of the present invention is not constituted any limitation.All employing equivalents or equivalence are replaced and the technical scheme of formation, all drop within the rights protection scope of the present invention.

Claims (8)

1. the joint of robot driver of a stiffness variable is characterized in that comprising:

Joint drive motors (1),

Rigidity is regulated parts (5),

Output (6), it is connected mutually with the joint of robot connecting rod,

The rigidity deceleration component is used for regulating the equilbrium position of output (6) under the different loads effect.

2. according to the joint of robot driver of the stiffness variable of claim 1, it is characterized in that the rigidity deceleration component comprises:

Harmonic speed reducer (2), shell/frame (3), bearing (4),

Rigidity is regulated parts (5) and is connected with the rigidity deceleration component, and rigidity is regulated parts (5) and being comprised:

A flexible rack (13) and

The gear pair rigidity governor motion that one pair is arranged along the axis antisymmetry of flexible rack (13), spur gear (9), its with flexible rack (13) between be that conjugation meshes,

Wherein

The rigidity output shaft (7) of the two ends of flexible rack (13) and harmonic speed reducer (2) is connected,

Under no angular deformation situation, the intersect vertical axis of the path of contact of flexible rack (13) and rigidity output shaft (7).

3. according to the joint of robot driver of the stiffness variable of claim 2, it is characterized in that:

The driving-chain of rigidity governor motion (5) comprising:

Rigidity is regulated motor (12), and the axis normal of its axis and rigidity output shaft (7) is arranged, is used for driving bevel pinion (11) rotation of bevel gear centering;

The bevel gear wheel of bevel gear centering (10) is coaxial with spur gear (9), and bevel gear wheel (10) drives spur gear (9) and rotates;

Slide block (14), it is regulated parts (5) with rigidity and is connected mutually,

Square guide rail (15), it matches with slide block (14), and it is mobile along square guide rail (15) to make rigidity regulate parts (5);

Cross-bearing (8), it is included in the output (6), and concentric with bearing (4)

Wherein

Flexible rack (13) is fixing with respect to shell (3), thereby it is mobile along flexible rack (13) to make rigidity regulate parts (5),

Square guide rail (15) is connected mutually with the output that contains cross-bearing (8) (6), and the intersect vertical axis of the axis of square guide rail (15) and output (6),

Thereby, when rigidity is regulated motor (12) running, cause that rigidity adjusting parts (5) are with respect to the change of the axial line distance of rigidity output shaft (6).

4. according to the joint of robot driver of the stiffness variable of claim 3, it is characterized in that:

By using rigidity governor motion (5A) that a secondary antisymmetry arranges and (5B), it is adjustable to have realized that forward and reverse joint stiffness is.

5. according to the joint of robot driver of the stiffness variable of claim 4, it is characterized in that:

Regulate in rigidity under the just commentaries on classics driving of motor (12), rigidity is regulated parts (5A) and is moved to the axis direction near output (6), then the distance of the axis of rigidity adjusting parts and rigidity output shaft (7) reduces, radial load from the corresponding spur gear of forwards/reverse loading moment (9) of output (6) increases, cause the bigger amount of deflection of flexible rack (13), namely joint stiffness reduces;

Otherwise, regulate in rigidity under the counter-rotating driving of motor (12), rigidity is regulated parts (5A) and is moved to the axis direction that deviates from output (6), then rigidity is regulated the distance increase of the axle of parts and rigidity output shaft (7), radial load from the corresponding spur gear of forwards/reverse loading moment (9) of output (6) reduces, cause the less amount of deflection of flexible rack (13), namely joint stiffness increases.

6. according to the joint of robot driver of the stiffness variable of claim 5, it is characterized in that:

Looking flexible rack (13) is spring beam, and amount of deflection is converted joint angle distortion, and joint stiffness K and rigidity adjusting motor (12) displacement σ's is square relevant so, i.e. K=f (σ ²), thereby the non-linear adjusting of realization joint stiffness.

7. according to the joint of robot driver of the stiffness variable of claim 6, it is characterized in that:

Two rigidity are regulated parts 5A and 5B carries out independent control respectively, then just can realize/the oppositely asymmetric adjusting of rigidity.

8. according to the joint of robot driver of the stiffness variable of claim 6, it is characterized in that:

Joint drive motors (1) and rigidity are regulated motor (12) and are adopted commercial servomotor.

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