CN105313117A - Adjustable-stiffness driver based on non-linear elastic element and driving method thereof - Google Patents

Abstract

The invention discloses an adjustable-stiffness driver based on a non-linear elastic element. The adjustable-stiffness driver based on the non-linear elastic element comprises a control circuit, a microprocessor, driving motors, rotating shafts, a speed reduction mechanism, non-linear springs and gear worms. The invention further discloses a driving method for driving the adjustable-stiffness driver based on the non-linear elastic element. The method comprises the following steps: 1, calculating to obtain expansion amount of the two non-linear springs through the microprocessor according to the given output torque and output stiffness; 2, transmitting the corresponding calculating results to the two driving motors through the microprocessor in a PD control manner, and then outputting the corresponding torque to the corresponding rotating shafts through the driving motors; 3, converting the torque outputted by the two driving motors into horizontal tension forces through the two gear worms, so as to correspondingly change the expansion amount of the two non-linear springs; 4, outputting the corresponding adjustable stiffness and torque in real time through the driver according to the expansion amount of the two non-linear springs. The adjustable-stiffness driver based on the non-linear elastic element and the driving method have the advantages that hardware devices are simplified, and a space is saved.

Description

Based on adjustable rigidity driver and the driving method thereof of non-linear elastic element

Technical field

The present invention relates to the technology that a kind of control algolithm and mechanical designing technique combine, in particular to a kind of adjustable rigidity driver based on non-linear elastic element and driving method thereof, the present invention controls frame for movement by control module design relevant control algorithm and realizes given moment, finally realizes the joint driver of adjustable rigidity.

Background technology

Nowadays, rapidly, demand is large, the design cycle is long in Robot industry development.In the urgent need to developing the hardware platform of a set of standardized, set machine in normal service people application module, be conducive to the cost and the R&D risk that reduce robot application like this.Therefore robot modularized research becomes emphasis, particularly robot modularized design.According to robot common function, it is decomposed from mechanism and control, forms multiple functional module with standalone feature, by reconstruct, the required robot modeling of composition application.

Equally, along with robot is more and more extensive in the application of the industry-by-industry such as industry, space flight, medical treatment, service, also get more and more with the chance that people is mutual, ensure that robot is becoming domestic and international primary study target with security when environment or human interaction.

Conventional machines people design is in order to ensure terminal position operation accurately, and the high-gain of rigidity that adopts controls more, carries out action according to the route planned in advance, completes dullness and the work that repeats.But when end effector of robot and surrounding environment come in contact, be easy to the impact being subject to surrounding environment, its human-computer interaction security is not high.If after combining contact force control, the requirement to position precision controlling just can be loosened.Simultaneously; when robot is subject to suddenly more powerful effect time; conventional machines people may because the characteristic of its rigid machine people can allow joint of robot place be subject to certain wearing and tearing; if and adopt variation rigidity joint driver; spring between motor and joint link lever can play cushioning effect; the safety of each parts of available protecting robot, completes the Flexible Control to robot.Therefore, scientist proposes the design of variation rigidity, has the passive security of compliant mechanism simultaneously, has control accuracy again, ensure that the security of man-machine interaction.

In these years also a lot of patent is placed on focus on the variation rigidity joint of robot, as follows respectively:

China publication number: CN104669261A, title: a kind of can a kind of method of adjustment of synchronous adjustment displacement-type variation rigidity joint driver and joint of robot rigidity.This invention adopts one can synchronous adjustment displacement-type variation rigidity joint driver, stiffness equivalent drive motors driven wheel is utilized to roll on flexible rack, change the stress point of flexible rack, make flexible rack generation deflection deformation in various degree, thus reach the object of variation rigidity.This invention can be measured accurately and adjust rigidity, but structure is comparatively complicated, assembling difficulty, and easily occurs deviation in extreme environment distortion such as high temperature, and the scope of application is wideless.

China publication number: CN104440936A, title: a kind of joint of robot of stiffness variable.In this invention, external force is produced corresponding frictional force by friction disc device, utilize the frictional behavior of friction plate to carry out stiffness tuning.This invention can change joint stiffness when being subject to larger external impacts, but this invention is due to structure restriction, only can play the preliminary effect regulating rigidity, can not the rigidity of accurate adjusting joint.

Summary of the invention

Primary and foremost purpose of the present invention is that the shortcoming overcoming prior art is with not enough, a kind of adjustable rigidity driver based on non-linear elastic element is provided, this adjustable rigidity driver is according to the design of variation rigidity joint driver, controlled by relational computation algorithm, structure is simple, not high to assembly hardware matching requirements, and be convenient to control.

Another object of the present invention is to overcome the shortcoming of prior art and deficiency, provide a kind of and drive the described driving method based on the adjustable rigidity driver of non-linear elastic element.

Primary and foremost purpose of the present invention is achieved through the following technical solutions: a kind of adjustable rigidity driver based on non-linear elastic element, mainly comprises control circuit, microprocessor, drive motors, rotating shaft, reducing gear, nonlinear spring and gear worm.Described microprocessor is connected on by two drive motors, microprocessor and drive motors pass through rotating shaft, reducing gear is connected with nonlinear spring with gear worm, two nonlinear springs lay respectively at the both sides of bull stick, relaxed state is in when not stressed, bull stick center is connected to connecting rod, connects next joint driver; The end of module of each joint driver all has a shaft portion to be used for the rigidity of exporting change and moment pass to next module;

The described adjustable rigidity driver based on non-linear elastic element mainly comprises following functional unit:

Microprocessor: be connected near drive motors, is used for controlling drive motors, and then controls the dilatability of nonlinear spring.Each when External Force Acting time, microprocessor transmits the moment and rigidity that are exported by a upper module, by the corresponding corresponding stroke calculating two nonlinear springs in this module, and the data obtained is passed in drive motors.Control for reaching accurate more rapidly, microprocessor uses PD to control.

Drive motors: be fixed on by microprocessor, be used for driving nonlinear spring, the corresponding information that microprocessor calculates by drive motors outputs in reducing gear, then by gear worm, the torque axis on motor shaft is before changed to lateral pull, namely changes into the controlled quentity controlled variable of the dilatability controlling nonlinear spring.

Nonlinear spring: nonlinear spring and common spring different, the difference of immanent structure (nonlinear spring is different at its different position density) determines square being directly proportional of the elastic force right and wrong Hookean spring stroke that nonlinear spring produces.Nowadays market there is the nonlinear spring be applicable under various occasion.So no matter be in the various specific situation such as high-temperature condition or adverse circumstances, there is corresponding nonlinear spring to meet the demands, this patent so just can be made to be applicable to the various environment of various situation, and be easy to maintenance.

Connecting rod: be in two nonlinear spring joints, be used for output module produce moment and rigidity.

Adjustable rigidity driver based on non-linear elastic element of the present invention can be divided into control module and these two parts of mechanical realization, at mechanical realization in this part, rotated by drive motors and relevant torque is provided, by gear worm, torque axis is turned to pulling force again, pull nonlinear spring, make nonlinear spring produce deformation.Two nonlinear springs act on bull stick simultaneously, produce output torque, export adjustable rigidity simultaneously.Control module, by algorithm design, realizes given output rigidity and moment.The present invention starts with from control module, utilizes relevant control algorithm, with mechanical realization acting in conjunction, not only simplify hardware unit, save space, reduce the requirement to assembling, and the stiffness variation of joint driver steadily changes along with external world's change, has very strong practicality.

Another object of the present invention is achieved through the following technical solutions: a kind ofly drive the described driving method based on the adjustable rigidity driver of non-linear elastic element, comprises the following steps:

Step 1, microprocessor are according to given output torque and export the stroke that Rigidity Calculation obtains two nonlinear springs;

Step 2, microprocessor control corresponding result of calculation to pass to two drive motors by PD, and drive motors exports corresponding moment in each axis of rotation;

The moment that two drive motors export is converted to horizontal pull by step 3, two gear worms respectively, changes the stroke of two nonlinear springs respectively;

Step 4, driver export corresponding adjustable rigidity and moment in real time by two nonlinear springs stroke separately.

The present invention has following advantage and effect relative to prior art:

1. present invention achieves rigidity adjustableization of joint driver, compare traditional rigidity joint, in the instantaneous high-strength impact masterpiece used time, self compliant characteristic can be utilized, Saving cortilage connecting rod, each position of whole robot is played a very good protection.

2. the joint driver of stiffness variable of the present invention, structural design is compact, and outward appearance is small and exquisite, the user demand under energy meeting spatial restraint condition.

3. the joint driver of stiffness variable of the present invention, in mechanism, nonlinear spring can storage power, and microprocessor calculates fast, is a kind of next-generation drive of efficient energy-saving.The present invention pays attention to algorithm design, it is no longer pure Machine Design, obtain connecting each other between input position and output torque rigidity by design respective algorithms, and utilize this contact to calculate corresponding nonlinear spring dilatability and then obtain ideal output torque and export rigidity.

Accompanying drawing explanation

Fig. 1 is nonlinear spring and bull stick position and operation principle schematic diagram in the present invention.

Fig. 2 builds variation rigidity joint driver frame for movement Part I schematic diagram based on non-linear elastic element in the present invention.

Fig. 3 builds variation rigidity joint driver frame for movement Part II schematic diagram based on non-linear elastic element in the present invention.

Fig. 4 the present invention is based on the algorithm flow that non-linear elastic element builds variation rigidity joint driver.

Detailed description of the invention

Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention are not limited thereto.

Embodiment

As shown in Figure 4, a kind ofly drive the described driving method based on the adjustable rigidity driver of non-linear elastic element, mainly comprise the following steps:

Step 1, as shown in Figure 1, of the present invention is a kind of adjustable rigidity driver based on non-linear elastic element, mainly based on the nonlinear spring of first in Fig. 11 and second nonlinear spring 2.The relation of these two nonlinear springs and telescopic spring amount is no longer simple linear relationship, but with the square of stroke.

That is:

F＝kx ²，(1)

In above formula, F is the elastic force that nonlinear spring produces, and k is proportionality coefficient, and be a constant, x is the stroke of nonlinear spring.As microprocessor output nonlinear spring corresponding generation stroke x ₁and x ₂time, the size of the power produced respectively as Fig. 1 first nonlinear spring 1 and second nonlinear spring 2 is:

$f_1={\mathrm{kx}}_1^2,---\left(2\right)$

$f_2={\mathrm{kx}}_2^2,---\left(3\right)$

In formula (2) and formula (3), f ₁and f ₂represent first nonlinear spring 1 and second power playing non-linear spring 2 and produce respectively, x ₁and x ₂represent the stroke of first nonlinear spring 1 and second nonlinear spring 2 respectively, and k is the proportionality coefficient of first nonlinear spring 1 and second nonlinear spring 2.

Step 2, as shown in Figure 3, comprise microprocessor 4 and mechanical realization Part I, mechanical realization Part I comprises first motor 5 and second motor 6 as drive motors, first rotating shaft 7 and second rotating shaft 8 are responsible for the moment of torsion that drive motors produces and are exported, first reducing gear 9 and second reducing gear 10 are responsible for reduction of speed and improve output torque, first gear 11, first worm screw 13 and second gear 12, second worm screw 14 forms two gear worms, output torque is converted to horizontal pull, controls the stroke of nonlinear spring.

As shown in Figure 4, comprise mechanical realization Part II, comprise first worm screw 13 and second worm screw, 14, first nonlinear spring 15 and second nonlinear spring 16 and export bull stick 17.

Microprocessor and the relation between output torque and rigidity will be introduced in detail below.

For the given output torque τ of joint driver, the elastic force f that it and two nonlinear springs produce ₁and f ₂relation as follows:

τ＝f ₁L ₁-f ₂L ₂，(4)

In above formula, τ is bull stick 17 place output torque, f ₁and f ₂represent elastic force suffered by first nonlinear spring 15 and second nonlinear spring 16 respectively, and L ₁and L ₂representing first nonlinear spring 15 and second stressed place of nonlinear spring 16 distance to rotating shaft respectively, is namely the arm of force of first nonlinear spring 15 and second nonlinear spring 16 respectively.

And two arm of forces can be expressed as respectively:

L ₁＝L+x ₁，(5)

L ₂＝L+x ₂，(6)

In above formula, as shown in Figure 3, L ₁and L ₂represent first nonlinear spring 15 and second stressed place of nonlinear spring 16 distance to rotating shaft respectively, L is the former length of first nonlinear spring 15 and second nonlinear spring 16, x ₁and x ₂represent the stroke of first nonlinear spring 15 and second nonlinear spring 16 respectively.

Then arrange various above, bull stick place output torque be expressed as:

$\mathrm{\τ}={\mathrm{kx}}_1^2(L+x_1)-{\mathrm{kx}}_2^2(L+x_2),---\left(7\right)$

In above formula, τ is bull stick 17 place output torque, and k is the proportionality coefficient of first nonlinear spring 15 and second nonlinear spring 16, and L is the former length of first nonlinear spring 15 and second nonlinear spring 16, x ₁and x ₂represent the stroke of first nonlinear spring 15 and second nonlinear spring 16 respectively.

The derivative of step 3, given output stiffness K ' be given output torque τ and rotational angle theta, that is:

$K^{\′}=\frac{d\mathrm{\τ}}{d\mathrm{\θ}},---\left(8\right)$

In above formula, K ' is for exporting rigidity, τ and θ represents output torque and corner respectively.

Consider the relation between bull stick place rotational angle theta and two nonlinear spring strokes:

θ＝(x ₁-x ₂)/R，(9)

In above formula, θ is bull stick 17 place corner, and R is the radius of bull stick 17 self, x ₁and x ₂represent the stroke of first nonlinear spring 15 and second nonlinear spring 16 respectively.The stroke x of then given output stiffness K ' and first nonlinear spring 15 and second nonlinear spring 16 ₁and x ₂between relation:

$K^{\′}=\frac{d}{d\mathrm{\θ}}\left({\mathrm{kx}}_1^2\right(L+x_1)-{\mathrm{kx}}_2^2(L+x_2\left)\right),---\left(10\right)$

That is:

$\begin{array}{c}{K}^{\′}=\frac{d}{d\mathrm{\θ}}({\mathrm{kx}}_1^{2}L-{\mathrm{kx}}_2^{2}L+{\mathrm{kx}}_1^3-{\mathrm{kx}}_2^3)\\ =\frac{d}{d\mathrm{\θ}}\left(kLR\right(x_1+x_2)\mathrm{\θ}+kR(x_1^2+x_1{x}_2+x_2^2\left)\mathrm{\θ}\right)\end{array},---\left(11\right)$

$K^{\′}=RkL(x_1+x_2)+Rk(x_1^2+x_1{x}_2+x_2^2),---\left(12\right)$

In above formula, K ' is given output rigidity, x ₁and x ₂be respectively the stroke of first nonlinear spring 15 and second nonlinear spring 16, R is the radius of bull stick 17 self, k is the proportionality coefficient of first nonlinear spring 15 and second nonlinear spring 16, and L is the former length of first nonlinear spring 15 and second nonlinear spring 16.Can obtain output connecting rod 17 place of mechanical realization two amount: output torque τ and export stiffness K '.

Step 4, control module can utilize given output torque and rigidity Design algorithm to obtain the stroke of corresponding two nonlinear springs, and then control to export.As shown in Figure 2, when produce more energetically or moment when, microprocessor 4 can make corresponding control instruction immediately, plays the effect of protection drive motors, joint and connecting rod, and for ensureing to control rapidly accurately, microprocessor adopts PD to control.

Microprocessor can according to given output torque τ and the stroke x exporting stiffness K ' calculate two nonlinear springs ₁and x ₂:

x ₁＝Rτ/K′+x ₂，(13)

$x_2=\frac{-b+\sqrt{(b^2-4ac)}}{2a},---\left(14\right)$

In formula (13) and (14), x ₁and x ₂be respectively the stroke of first nonlinear spring 15 and second nonlinear spring 16, K ' is given output rigidity, and R is the radius of bull stick 17 self, and τ is the output torque at bull stick 17 place; A, b, c represent respectively:

a＝3Rk，(15)

b＝2RkL+3R ²τk/K′，(16)

c＝R ²τkL/K′+(R ³kτ ²/(K′) ²-K′，(17)

Formula (15), (16) and in (17), a, each unknown quantity in b, c expression (14), R is the radius of bull stick 17 self, k is the proportionality coefficient of first nonlinear spring 15 and second nonlinear spring 16, L is the former length of first nonlinear spring 15 and second nonlinear spring 16, K ' for given output rigidity, τ be the output torque at bull stick 17 place.

As shown in Figure 4; microprocessor just can according to given moment and given output rigidity; calculated by respective algorithms and PD control; control the stroke of two nonlinear springs timely and accurately; reach eventually through control nonlinear spring stroke and export adjustable rigidity; realize Flexible Control, Saving cortilage driver, improve the security of man-machine interaction.

Above-described embodiment is the present invention's preferably embodiment; but embodiments of the present invention are not restricted to the described embodiments; change, the modification done under other any does not deviate from Spirit Essence of the present invention and principle, substitute, combine, simplify; all should be the substitute mode of equivalence, be included within protection scope of the present invention.

Claims (7)

1. based on an adjustable rigidity driver for non-linear elastic element, it is characterized in that, comprising: control circuit, microprocessor, drive motors, rotating shaft, reducing gear, nonlinear spring and gear worm;

Described microprocessor, according to the rigidity exported and moment, calculates the stroke of nonlinear spring, and controls drive motors;

Described drive motors under control of the microprocessor, exported the moment of torsion produced by rotating shaft, improve output torque through reducing gear reduction of speed simultaneously, be converted to after pulling force through gear worm, control the stroke of nonlinear spring, thus control the change exporting rigidity and moment.

2. as claimed in claim 1 based on the adjustable rigidity driver of non-linear elastic element, it is characterized in that, described control module utilizes nonlinear spring stroke and the relation between output torque and rigidity, designs specific control algolithm and controls to export rigidity and moment.

3. as claimed in claim 1 based on the adjustable rigidity driver of non-linear elastic element, it is characterized in that, the quantity that described nonlinear spring is is two, two nonlinear springs are respectively in bull stick both sides, and two in parallel nonlinear springs are proportional to the coefficient of elasticity sum of two nonlinear springs together with the coefficient of elasticity of bull stick entirety; When joint driver is in mechanism, the coefficient of elasticity of described nonlinear spring entirety adopts the derivative of its output torque and time corner to represent, the output torque of two nonlinear springs is proportional to the difference of the elastic force that two nonlinear springs produce.

4. as claimed in claim 3 based on the adjustable rigidity driver of non-linear elastic element, it is characterized in that, square being proportionate of described two nonlinear springs and relevant position.

5. as claimed in claim 3 based on the adjustable rigidity driver of non-linear elastic element, it is characterized in that, described two nonlinear springs are all ined succession drive motors, under the effect of control module, control the size exporting rigidity.

6. as claimed in claim 3 based on the adjustable rigidity driver of non-linear elastic element, it is characterized in that, described two nonlinear springs are identical, described two nonlinear springs all connect gear worm by connecting rod, two nonlinear springs are subject to driving and the control of drive motors and microprocessor, and connecting rod exports adjustable rigidity size and moment size.

7. drive a driving method for the adjustable rigidity driver based on non-linear elastic element according to claim 1, it is characterized in that, comprise the following steps:

Step 1, microprocessor are according to given output torque and export the stroke that Rigidity Calculation obtains two nonlinear springs;

Step 2, microprocessor control corresponding result of calculation to pass to two drive motors by PD, and drive motors exports corresponding moment in each axis of rotation;

The moment that two drive motors export is converted to horizontal pull by step 3, two gear worms respectively, changes the stroke of two nonlinear springs respectively;

Step 4, driver export corresponding adjustable rigidity and moment in real time by two nonlinear springs stroke separately.