CN100436237C - Human-imitating double-foot robot artificial leg - Google Patents

Abstract

The present invention relates to an artificial leg for a human simulating biped robot, which belongs to the technical field of robots. The present invention comprises a hip joint, a knee joint, an ankle joint, a foot, a thigh link and a shank link. The present invention is characterized in that a knee joint drive motor is installed on the thigh link positioned between the hip joint and the knee joint, and the knee joint is two four-link enclosed chain structure. The knee joint drive motor is connected with a back link of each four-link by a parallel four-link mechanism. A stop block is fixed at the front end of each four-link, and an encoder is installed at a rotary shaft of the upper end of a front link of each four-link. the present invention has the advantages that the height between the foot and the ground is increased, and the foot can have a better obstacle avoidance ability in the process of walking; moreover, a shank can not touch the ground in the process of swinging, and the stability and the high efficiency of walking can be increased. The mass distribution of the leg further approaches to the leg of a human, the overall structure is compact, and the transmission accuracy is high.

Description

A kind of human-imitating double-foot robot artificial leg

Technical field

The invention belongs to the Robotics field, particularly relate to a kind of human-imitating double-foot robot artificial leg.

Technical background

The existing shank disabled person of China is about more than 30 ten thousand, and annually increases about 1.5 ten thousand people, if people's shank for some reason from cut more than the knee joint, will bring great misery to himself and household.They are looking forward to the appearance of the intelligent bionic leg with suitable China's actual conditions.Be accompanied by the development of microelectronic technique and control technology, the nineties in 20th century, the medical science of recovery therapy area research comes compensatory disabled person's incomplete limbs with the intelligent artificial limb of microprocessor control.Intelligent artificial limb be a kind of can be fine the device of the part or all of lower limb function of replacement disabled person, can help the disabled person to stand, walking, stair activity, run even join into sports as the normal person, accomplish " activity freely ".It is that technology such as collection machinery, electronics, control, artificial intelligence, biologic medical are the frontier nature of one, the research topic of multidisciplinary intersection.At present, developed intelligent bionic leg product abroad, but cost an arm and a leg, technical know-how, and the service on also put in place inadequately.In the development process of lower limb intelligent artificial limb, need do in a large number intelligent artificial limb, the experiment of repetition, multiple gait.Obviously, to do such experiment be unpractical if allow a disabled person dress intelligent artificial limb, because may cause unnecessary damages to the disabled person, and the disabled person also can't satisfy the experiment of desired a large amount of, good reproducibility, various gaits.So the exploitation of intelligent artificial limb needs a desirable experiment porch, the effect of this experiment porch is exactly to replace the disabled person who dresses intelligent artificial limb to do various experiments.This will realisticly test platform and have good personification, various walking step states that can the anthropomorphic dummy.

We analyze the leg of common both legs walking robot and the essential difference that people's leg structurally exists and the influence of generation: human leg bone's bone mechanism humanly forms through very long evolution, should be best suited for the biometric mechanisms of both legs walking.People's leg knee joint is mainly by external condyle, tibial plateau, kneecap, ligamentaum cruciatum ACL and PCL, muscle and neural composition the in the femur.Biomedical research shows that distal part of femur and shin bone upper end mating surfaces out-of-shape are bent and stretched in the activity at knee joint, and existing rolling has slip again between two surfaces.Ligament plays lubricated and buffering effect between bone.Knee joint horizontal rotating shaft position in the activity of bending and stretching is inconstant, and certain moving can be arranged, and its center of curvature is that (Instant Centre ofRotation, ICR) motion track is pressed the J-shaped curvilinear motion to instantaneous center of turn, as shown in Figure 1.The joint is driven by inside and outside both sides muscle fore and aft motion, as shown in Figure 2.Therefore, in the human locomotion process, large and small leg length changes, and knee joint ICR also changes, and can improve the less touch with the ground height under the bent angle in the wrong in less joint.Wherein thigh and calf length be meant thigh and calf connecting rod up and down intersection point respectively and the distance between hip joint and the ankle-joint center-point.Simultaneously, the variation of knee joint ICR can be regulated ground reaction force to kneed level of torque, also can influence hip joint and rotate kneed slaved operation, so the stability and the high efficiency of walking had direct influence.And present most both legs walking robot, for the foundation of mechanism design, control, math modeling and the convenience of resolving, joint model is compared human synovial and has been carried out a large amount of simplification.Especially active both legs walking robot, knee joint have all been continued to use industrial machine philtrum two connecting rod hinge knee-joint mechanisms commonly used, and (Centre ofRotation's center of turn CR) immobilizes, as shown in Figure 3.

Difference on this knee joint structure causes guaranteeing to support phase antihunt means difference, people's leg is being stood and is being in the support phase time, knee joint is a straight configuration, and the common double robot leg is at standing state or be in the support phase time, mostly crooked both legs, for preventing to impact, pin is set level earlier before landing always, and causes the speed of travel slow.Another difference of the leg of people's leg and common double biped robot is: people's pin has flexibility, and the pin of robot is a rigidity.Because the pin of robot lacks flexible, does not have buffer action, for avoiding in the process of walking must controlling from walking posture, thereby influenced the personification of robot gait in the face of the impact of pin.

Summary of the invention

In order to solve the problem of above-mentioned existence, the invention provides a kind of human-imitating double-foot robot artificial leg, it makes robot have anthropomorphic walking step state, and reduces the difficulty of control, with the test platform of this robot as the development intelligent artificial limb.

Artificial leg of the present invention comprises hip joint, knee joint, ankle-joint, pin, big leg connecting rod and little leg connecting rod, on the big leg connecting rod between hip joint and the knee joint, the knee joint drive motor is installed, knee joint is two four connecting rod sealed joint structures, the knee joint drive motor is connected by the back bar of parallel four-bar linkage with kneed two four connecting rod sealed joint structures, front end on two four connecting rod sealed joint structures is fixed with block, in the rotating shaft on the preceding bar of one four connecting rod sealed joint structure coder is installed.

Two the four connecting rod sealed joint structures at its knee joint place: be to be respectively equipped with one group of four connecting rod in the knee joint both sides, between connect by rotating shaft.Parallel four-bar linkage is that a connecting rod forms with big leg connecting rod.Ankle-joint is an inverted U, interior parallel two rotating shafts that are equipped with of inverted U structure, in a rotating shaft, the ankle-joint motor is installed, in inverted U structural outer one side, two roller end are separately installed with clearance elimination gear, the transmission that is meshed of two clearance elimination gears is equipped with harmonic speed reducer in the rotating shaft that the ankle-joint motor is installed near a side of clearance elimination gear.Pin is flexible energy storage artificial foot, is installed in the rotating shaft of below in interior two parallel shafts of inverted U structure.

Advantage of the present invention is that knee joint adopts four connecting rod sealed joint structures, the less touch with the ground height that helps improving, and the enhancing pin has in the process of walking better keeps away the barrier ability, and can not run into ground in the shank swing process, strengthens the stability and the high efficiency of walking.Adopt parallel four-bar linkage that motor driving moment is delivered to the knee joint place, make the mass distribution of leg more approach people's leg, make kneed structure compact more; From the dynam angle, can reduce requirement to hip joint motor-driven moment, reduce the degree of coupling of drive torque, make kinetic model simpler, be easy to control more.Ankle-joint adopts harmonic speed reducer to add the clearance elimination gear transmission, more compact structure, and also transmission accuracy improves; Adopt flexible energy storage artificial foot, make it approach people's pin.

Description of drawings

Fig. 1 is an integral structure scheme drawing of the present invention;

Fig. 2 is a knee joint structure scheme drawing among the present invention;

Fig. 3 is knee joint driving, a drive mechanism scheme drawing among the present invention;

Fig. 4 is an ankle-joint structural representation among the present invention;

Fig. 5 is people's leg knee joint structure scheme drawing;

Fig. 6 is that people's leg knee joint muscle drives scheme drawing;

Fig. 7 is that existing single-axis knee joint rotates scheme drawing;

Fig. 8 is people's leg knee joint equivalence conversion scheme drawing;

Fig. 9 is single shaft and polycentric knee joint swing terrain clearance contrast scheme drawing, and wherein (a) is single-axis knee joint, (b) is polycentric knee joint;

Figure 10 is the scheme drawing that concerns that the present invention supports opposing force active line and ICR, and wherein: a supports the phase initial stage, and b is support phase mid-term, and c is support phase late period;

Rotation of Figure 11 rigid body and translation scheme drawing;

Figure 12 is a mechanism size definition scheme drawing of the present invention;

Figure 13 is an ankle-joint locus of points tracking effect curve synoptic diagram among the present invention;

Figure 14 is the optimizer diagram of circuit.

1. hip joints among the figure, 2. big leg connecting rod, 3. knee joint drive motor, 4. parallel four-bar linkage, 5. knee joint, 6. little leg connecting rod, 7. ankle-joint, 8. pin, 9. block, 10. knee joint connecting rod, 11. coder, 12. ankle-joint motors, 13. ankle-joint rotating shafts, 14. muscle, 15. clearance elimination gears, 16. femorals head, 17. shin bone, 18. muscle inboards, the 19. muscle outside.

The specific embodiment

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

As shown in Figure 1, the present invention includes hip joint 1, knee joint 5, ankle-joint 7, pin 8, big leg connecting rod 2 and shank connecting rod 6, on the big leg connecting rod 2 between hip joint 1 and the knee joint 5, knee joint drive motor 3 is installed, knee joint 5 is two four connecting rod sealed joint structures, knee joint drive motor 3 is connected with the back bar of two four connecting rod sealed joint structures of knee joint 5 by parallel four-bar linkage 4, front end on two four connecting rod sealed joint structures is fixed with block 9, in the rotating shaft on the preceding bar of two four connecting rod sealed joint structures coder 11 is installed.

Two the four connecting rod sealed joint structures at knee joint place as shown in Figure 2, are to be respectively equipped with one group of four connecting rod in knee joint 5 both sides, between connect by rotating shaft.Parallel four-bar linkage 4 is that a connecting rod forms with big leg connecting rod 2 as shown in Figure 3.As shown in Figure 4, ankle-joint 7 is an inverted U, interior parallel two rotating shafts that are equipped with of inverted U structure, in a rotating shaft, ankle-joint motor 12 is installed, two roller end of inverted U structural outer one side are separately installed with clearance elimination gear 15, two clearance elimination gear engaged transmission are equipped with harmonic speed reducer in the rotating shaft that the ankle-joint motor is installed near a side of clearance elimination gear.Pin 8 is flexible energy storage artificial foot, is installed in the ankle-joint rotating shaft 13 of below in interior two parallel shafts of inverted U structure.

Knee joint drive motor 3 drives parallel four-bar linkage 4 motions among the present invention, with four connecting rods of transmission of power to knee joint 5, makes four connecting rods drive shank, ankle-joint and pin motion, reaches the effect of emulation people leg.

Be people's leg knee joint structure scheme drawing as shown in Figure 5, Fig. 6 leg knee joint muscle of behaving drives scheme drawing, Fig. 7 is the single-axis knee joint scheme drawing, because the position of the instantaneous center of rotation ICR of four bar linkage knee joint changes in rotation process, thereby cause thigh and calf length in swing, to change, as shown in Figure 9, so when the bent angle θ in the wrong of knee joint was identical, it was different that two kinds of knee joints make the terrain clearance of pin; The variation of knee joint ICR, can regulate ground reaction force to kneed level of torque, also can influence hip joint and rotate, so the stability and the high efficiency of walking had direct influence kneed slaved operation, support the relation of phase ground reaction force active line and ICR, as shown in figure 10.The variation of knee joint instantaneous center of rotation ICR, can regulate ground reaction force GRF to kneed level of torque, also can influence hip joint Hip (Hip is that the English of hip joint is represented) and rotate, so the stability and the high efficiency (being energy consumption) of walking had direct influence kneed slaved operation.The relation of support phase ground reaction force active line and ICR as shown in figure 10.A figure is the phase initial stage of supporting, and heelstrike promptly, the extended line of ground reaction force GRF is in the front of instantaneous center of rotation, and the moment that GRF produces makes leg rotate counterclockwise around ICR, but the limited block of this rotation blocks, so leg can only stretch; In the mid-term that phase is supported in b figure expression, promptly sole falls to normal price on the ground, and at this moment the extended line of GRF moves backward, but still can guarantee leg is stretched; C figure supports phase latter stage, and heeloff and tiptoe lands promptly, at this moment the extended line of GRF has moved on to the back of ICR, and the moment that GRF produces will make the leg bending, for the swing of leg is prepared mutually.

In the design process of the present invention, knee design most importantly.Design is done to specify with regard to four connecting rod multiaxis bionic knee joint below:

1, Bionic Design requirement

The artificial leg size of the present invention similar human both legs size of should trying one's best, so in design of the present invention, be reference object with the Chinese man that grows up, the analogy method of designing is adopted in mechanism's population parameter design.

The references object human parameters is as shown in table 1:

Table 1:

Project	Value
		Height	1.76m
Thigh length	0.46m
		Shank length	0.48m
The pin height	0.1m
		The pin width	0.07m
Pin is long	0.25m
		The ankle-joint center-point is the position of face (apart from heel) under foot	0.055m

Thigh weight	7.725kg, account for population proportion 10.3%
		Shank weight	3.225kg, account for population proportion 4.3%
Pin weight	1.125kg, account for population proportion 1.5%
		Normal leg speed	95～125 step/min
Step-length	150～160cm
		Go on foot wide	5～10cm
Length strides	75～83cm
		Gait cycle	0.45~0.6s
Support the phase ratio	40% (under the normal leg speed) of gait cycle
		Swing phase ratio	60% (under the normal leg speed) of gait cycle
Ankle-joint bends and stretches angular range	Waste time and bend 20 degree, the back of the body is stretched 15 degree
		Knee joint bends and stretches angular range	Fully stretch flexing 60 degree
Hip joint bends and stretches angular range	Anteflexion			30 the degree, after stretch 10 the degree

In when design, except that upper body, take into full account above-mentioned parameter designing, thus the mechanism parameter and the oad that artificial leg of the present invention are had approach very much with human body, range of motion is identical, fundamentally guarantees the personification of artificial leg walking.The parameter in last table, in design, also need consider: 10 to 30mm places, ground supports counter-force active line rear when the knee joint center should be positioned at the leg erectility, so that the support phase self-locking of knee-joint mechanism guarantees supporting ﹠ stablizing; Ankle-joint should be positioned at the knee joint back lower place, and the distance before and after both depends on the type with selected pin, field of prosthetic limbs be called artificial limb to line technology; The dorsiflex of pin and the sole of the foot are bent scope and are determined according to the type and the body weight of pin.

These character all are the characteristics that people's leg is had, and need satisfy in design, also are not have to consider in the both legs walking robot design in the past.The design of both legs walking robot in the past only pay attention to whole size and human body similar, do not pay close attention to joint swing characteristic, the details such as position relation of articulation center point between the standing state vertical coordinate.

2, four connecting rod polycentric knee joint synthesis of mechanism

Because it is a closing means chain that bionic leg kneed four connects mechanism, mechanism parameter designs than the open chain complexity.The design of bionic leg knee joint four-bar linkage parameter is a synthesis of mechanism problem, requirement is satisfied under the situation of people's leg pendulum angle relation at thigh and calf, the track that guarantees bionical knee joint fulcrum and ankle-joint fulcrum is identical with the track of people's leg corresponding joint center of turn, belong to the guiding of synthesis of mechanism rigid body (Rigid Body Guide, RBG) problem.Determining of parameter can be by the realization of multivariate computation optimization.

According to the requirement that proposes above, determine that the optimization aim function is to bionical knee joint rigid body guiding

$\min f\left(X\right)=\mathrm{<figure-callout\; id="1"\; label="min\; C"\; filenames="C20061004716900121.png,C20061004716900162.png"\; state="\{\{state\}\}">min</figure-callout>}\left[\begin{array}{c}{C}_{}\end{array}\right]\left[\begin{array}{c}{}_1\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\sqrt{{({\tilde{x}}_{\mathrm{kpi}}-x_{\mathrm{kpi}})}^2+{({\tilde{z}}_{\mathrm{kpi}}-z_{\mathrm{kpi}})}^2}\\ +{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="C20061004716900121.png,C20061004716900122.png"\; state="\{\{state\}\}">C</figure-callout>}}_2\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\left|\cos ({\mathrm{\&theta;}}_{\mathrm{ki}}-\mathrm{\&phi;})\right|\sqrt{{({\tilde{x}}_{\mathrm{api}}-x_{\mathrm{api}})}^2+{({\tilde{z}}_{\mathrm{api}}-z_{\mathrm{api}})}^2}\end{array}\right]---\left(1\right)$

St.l _imin＜l _i＜l _imax，max(x _ki)-min(x _ki)≤X _max，max(z _ki)-min(z _ki)≤Z _max

Wherein,

I=1...n represents the track hits;

x _Kpi, z _KpiThe Cartesian coordinates value of representing actual knee joint center of turn;

The Cartesian coordinates value of representing desirable knee joint center of turn;

x _Api, z _ApiThe Cartesian coordinates value of representing actual ankle-joint center of turn;

The Cartesian coordinates value of representing desirable ankle-joint center of turn;

${\mathrm{\&theta;}}_{\mathrm{ki}}={\mathrm{\&theta;}}_2^b-{\mathrm{\&theta;}}_5^b$ The expression shank is relatively for the pivot angle of the extended line of thigh;

C ₁, C ₂The expression coefficient of weight, C ₁+ C ₂=1.Because the track of ankle-joint center of turn is bigger to bionical properties influence than the track of knee joint center of turn, so general C ₂Compare C ₁Value a lot of greatly, the design: C ₁=0.2, C ₂=0.8.

Objective function first is used for estimating the performance of the desirable knee joint center of turn of actual knee joint center of turn track following track;

The objective function second portion is used for estimating the performance of the desirable ankle-joint center of turn of actual ankle-joint fulcrum track following track;

| cos (θ _Ki-φ) | be used to represent that the pose of shank is not of equal importance, φ represents very important attitude angle in the shank swing, generally is the shank pendulum angle of pin when arriving liftoff vertex.Do not need to consider the swing of thigh in the computation optimization,, carry out under the shank swing situation so the knee-joint mechanism parameter designing can be motionless at thigh.

Bionic leg knee joint center K _PThe point computing formula is

$K_P=\frac{1}{4}\underset{i=1}{\overset{4}{\mathrm{\&Sigma;}}}{K}_i---\left(2\right)$

First in the constraint condition is the length of connecting rod constraint, and second and third is the motion space constraint.

Be the calculation optimization target, at first will set up the transformation model between joint rotational angle and the key point spatial coordinates.Do not adopt the D-H parameter model at this.Because the D-H parameter is a kind of comprehensive parameters, can't characterize mechanism's detailed characteristics, be unfavorable for the Mechanism Optimization design.Find the solution four-bar linkage parameter optimization problem, at first need set up the relation between articulation center point Cartesian coordinates and the mechanism parameter.

(y θ) is planar rotation matrix to definition Rot, the rotation transformation matrix in the robotics coordinate transform just.Rotation matrix is affacted an existing translation to be had again on the rigid body of rotation, and the vector that constitutes with two some P, Q on the rigid body

With The position of expression rigid body, as shown in figure 11, then following formula is set up

$\left[\begin{array}{c}{x}_{Q2}-{\mathrm{<figure-callout\; id="2"\; label="x\; P"\; filenames="C20061004716900121.png,C20061004716900122.png"\; state="\{\{state\}\}">x</figure-callout>}}_P\\ 0\\ z_{Q2}-{\mathrm{<figure-callout\; id="2"\; label="z\; P"\; filenames="C20061004716900121.png,C20061004716900122.png"\; state="\{\{state\}\}">z</figure-callout>}}_P\end{array}\right]=\mathrm{Rot}(y,\mathrm{\&theta;})\left[\begin{array}{c}{x}_{Q1}-{\mathrm{<figure-callout\; id="1"\; label="x\; P"\; filenames="C20061004716900121.png,C20061004716900162.png"\; state="\{\{state\}\}">x</figure-callout>}}_P\\ 0\\ z_{Q1}-z_{P1}\end{array}\right]---\left(3\right)$

According to the rotation matrix definition, can obtain from formula (3)

$\left[\begin{array}{c}{\mathrm{<figure-callout\; id="2"\; label="x\; Q"\; filenames="C20061004716900121.png,C20061004716900122.png"\; state="\{\{state\}\}">x</figure-callout>}}_Q\\ 1\\ {\mathrm{<figure-callout\; id="2"\; label="z\; Q"\; filenames="C20061004716900121.png,C20061004716900122.png"\; state="\{\{state\}\}">z</figure-callout>}}_Q\end{array}\right]=\left[\begin{array}{ccc}\cos \mathrm{\&theta;}& x_{P2}-{\mathrm{<figure-callout\; id="1"\; label="x\; P"\; filenames="C20061004716900121.png,C20061004716900162.png"\; state="\{\{state\}\}">x</figure-callout>}}_P\cos \mathrm{\&theta;}-{\mathrm{<figure-callout\; id="1"\; label="z\; P"\; filenames="C20061004716900121.png,C20061004716900162.png"\; state="\{\{state\}\}">z</figure-callout>}}_P\sin \mathrm{\&theta;}& \sin \mathrm{\&theta;}\\ 0& 1& 0\\ -\sin \mathrm{\&theta;}& {\mathrm{<figure-callout\; id="2"\; label="z\; P"\; filenames="C20061004716900121.png,C20061004716900122.png"\; state="\{\{state\}\}">z</figure-callout>}}_P+x_{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="C20061004716900121.png,C20061004716900162.png"\; state="\{\{state\}\}">P</figure-callout>}1}\sin \mathrm{\&theta;}-{\mathrm{<figure-callout\; id="1"\; label="z\; P"\; filenames="C20061004716900121.png,C20061004716900162.png"\; state="\{\{state\}\}">z</figure-callout>}}_P\cos \mathrm{\&theta;}& \cos \mathrm{\&theta;}\end{array}\right]\left[\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="x\; Q"\; filenames="C20061004716900121.png,C20061004716900162.png"\; state="\{\{state\}\}">x</figure-callout>}}_Q\\ 1\\ z_{Q1}\end{array}\right]---\left(4\right)$

Formula (4) can be reduced to Q ₂=T ₂₁Q ₁, T in the formula ₂₁Be called an in-plane displancement matrix, be illustrated in the object of which movement process, the P point is by P ₁Move to P ₂Point, simultaneously

Rotated Q point coordinate conversion under the situation of θ angle, the P point is called and involves a little.For bionical knee joint K ₂, K ₃It is involving a little of ordering of A; K ₁Be again K ₂Involve a little; K ₄Be again K ₃Involve a little.Be to be rigidly connected between the each point, the space tracking of knee joint and ankle-joint center-point is by K ₁, K ₂, K ₃, K ₄, the A initial coordinate of ordering and connecting rod swing angle determine.The initial coordinate of 5 points is again by l ₂ ^b, l ₃ ^b, l ₄ ^b, l ₅ ^b, l ₉ ^b, l ₁₀ ^b, l ₁₁ ^b, l ₁₂ ^b, 10 mechanism parameters such as α, β determine, so mechanism's rigid body guiding optimal design parameter has 10.

With the optimization aim gait data that obtains as artificial leg design-calculated simulated object.Because variable is subjected to equation and inequality constrain, so this paper adopts quasi-Newton method and interior penalty method to be optimized calculating, its calculation process as shown in figure 12.May further comprise the steps:

1. given initializaing variable, control accuracy and constraint condition;

Initializaing variable is promptly optimized variable: at first the knee joint four-bar mechanism has l ₃ ^b, l ₄ ^b, l ₉ ^b, l ₁₀ ^bTotally 4 length of sides are adjustable.The position that next thigh is consolidated on the knee joint boxed rod also is adjustable, and its position can be with anchoring point to k ₁ ^bApart from l ₁₁ ^b, the thigh bar length l ₂ ^bAnd the angle α three between thigh bar and the boxed rod represents.Equally, shank also has 3 adjustable parameters: the anchoring point of shank on the knee joint lower link is to k ₂ ^bApart from l ₁₂ ^b, shank pole length l ₅ ^bAnd the angle β between shank bar and the lower link.As seen, whole bionic leg system have 10 parameters can be for adjusting.That is: $X={[l_2^b,l_3^b,l_4^b,l_5^b,l_9^b,l_{10}^b,l_{11}^b,l_{12}^b,\mathrm{\&alpha;},\mathrm{\&beta;}]}^l.$

Given initializaing variable: optimizing beginning, needing to give and optimize initial value of variable, according to constraint condition, in meeting the scope of constraint, optimizing the variable original bulk can be given arbitrarily, by optimizer, optimizes variable and approaches optimal result gradually.

Constraint condition:

A) bio-imitability condition

In the mechanism kinematic process, any except that satisfying performance requriements on each member, its movement position can not surpass the action radius of human body lower limbs.The one, knee-joint mechanism transtibial sockets in relative rotation all angles normal reasonably outward appearance is all arranged, and higher position is arranged at its instantaneous center of rotation of phase time of standing; The 2nd, knee-joint mechanism when work its each bar and hinge-point must be positioned at the action radius of normal human's lower limb; The 3rd, the scope of the flexion angles of knee-joint mechanism is less than 120 °.

Above-mentioned bio-imitability condition can solve by the qualification to the design variable span, that is:

$x_{i\min }^b\&le;x_i^b\&le;x_{i\max }^b,(i=\mathrm{1,2},...,10)$

B) dynamic profile reasonableness condition

For artificial limb knee-joint its profile and normal human's knee joint in motion process are matched, can be by to knee joint instantaneous center of rotation ICR (x _Icr, y _Icr) the change in location zone limited and realized.That is:

x _icrmin≤x _icr≤x _icrmax，y _icrmin≤y _icr≤y _icrmax

C) four bar knee joint closed chain constraint conditions

Bionic leg knee joint 4-bar sealed joint geometrical constraint can be represented following plural form:

$-{L_9^{b}e}^{j({\mathrm{\&theta;}}_2^b-\mathrm{\&alpha;})}-{{L^b}_{3}e}^{j{\mathrm{\&theta;}}_3^b}+{L^b}_{10}{e}^{j({\mathrm{\&theta;}}_5^b-\mathrm{\&beta;})}+{L_4^{b}e}^{j{\mathrm{\&theta;}}_4^b}=0$

Control accuracy: be exactly to optimize the condition that algorithm stops, in the optimization: when target function value≤1 * 10 ^-6, optimization stops, otherwise continues to optimize.

2. determine each coefficient of weight by constraint condition;

Different constraints is different to the influence of mechanism design, for outstanding this characteristics, gives different weights for the objective function different piece.Obviously, design is most important to artificial leg in the influence of the target trajectory of ankle-joint, so C ₁＜C ₂

3. the cycle number cycle=0 of computation optimization is set;

4. call the unconstrained minimization process, try to achieve the variable X that makes the penalty minimalization.The unconstrained minimization process can adopt multiple optimization algorithm to realize, what the design adopted is that " variable-metric method " optimizes algorithm, realizes by the VC programming.

5. judge || f (X) || whether≤ε sets up, if set up, forwarded for the 9th step to: obtained optimal solution, computation optimization finishes; Otherwise continue next step; Wherein || f (X) || be the optimization aim functional value, ε is the precision of setting previously 1 * 10 ^-6

6. call extrapolation procedure, try to achieve X ^(cycle)

Optimization is a process of approaching gradually, and each optimization all can obtain one than the better X as a result of preceding suboptimization ^(cycle),, will obtain optimal result by repeated multiple times optimization.Extrapolation procedure is " to find the solution X ^(cycle)" program, by calling in the program, try to achieve the variable X of this suboptimization ^(cycle)The result as the following initializaing variable value of suboptimization.

7. computation optimization cycle number Cycle=cycle+1 is set;

8. judge whether computation optimization cycle number Cycle≤MaxCycle sets up,, then returned for the 4th step if set up; If be false, think then to obtain optimal solution that computation optimization finishes;

The error control precision of optimizing result and setting is relevant.Optimizing the result might can not get optimal solution in the accuracy rating of setting, at this time should amplify control accuracy.MaxCycle is the largest optimization number of times, when in largest optimization number of times scope, do not try to achieve yet satisfy control accuracy as a result the time, program should stop, in order to avoid endless loop.

9. make X _Min=X ^(cycle), having obtained optimal solution, program can stop.X ^(cycle)Be each result who optimizes, X _MinIt is the optimal solution that we finally obtain.Optimize variable $X={[l_2^b,l_3^b,l_4^b,l_5^b,l_9^b,l_{10}^b,l_{11}^b,\mathrm{\&alpha;},\mathrm{\&beta;}]}^T.$

10. program stops.

Calculate by process optimization, promptly given initializaing variable value and dreamboat track after, the Automatic Program operation, all data computation all are to optimize algorithm routine according to design-calculated to calculate automatically, it is as shown in table 2 to optimize the result.The ankle-joint locus of points tracking effect of designed artificial leg in this example, as shown in figure 13.Figure 14 is the optimizer diagram of circuit.

Table 2

l 2 b	l 3 b	l 4 b	l 5 b	l 9 b	l 10 b	l 11 b	l 12 b	α	β
										0.447	0.089	0.04	0.389	0.059	0.079	0.001	0.027	2.49	1.57

Claims (5)

1, a kind of human-imitating double-foot robot artificial leg, comprise hip joint, knee joint, ankle-joint, pin, big leg connecting rod and little leg connecting rod, it is characterized in that on the big leg connecting rod between hip joint and the knee joint, the knee joint drive motor being installed, knee joint is two four connecting rod sealed joint structures, the knee joint drive motor is connected by the back bar of parallel four-bar linkage with kneed two four connecting rod sealed joint structures, front end on two four connecting rod sealed joint structures is fixed with block, in the rotating shaft on the preceding bar of one four connecting rod sealed joint structure coder is installed.

2, a kind of human-imitating double-foot robot artificial leg according to claim 1 is characterized in that two the four connecting rod sealed joint structures at described knee joint place: be to be respectively equipped with one group of four connecting rod in the knee joint both sides, between connect by rotating shaft.

3, a kind of human-imitating double-foot robot artificial leg according to claim 1 is characterized in that described parallel four-bar linkage is that a connecting rod forms with big leg connecting rod.

4, a kind of human-imitating double-foot robot artificial leg according to claim 1, it is characterized in that described ankle-joint is an inverted U, interior parallel two rotating shafts that are equipped with of inverted U structure, in a rotating shaft, the ankle-joint motor is installed, two roller end in inverted U structural outer one side are separately installed with clearance elimination gear, two clearance elimination gears are meshed, and near a side of clearance elimination gear harmonic speed reducer are installed in the rotating shaft that the ankle-joint motor is installed.

5, a kind of human-imitating double-foot robot artificial leg according to claim 4 in the rotating shaft below it is characterized in that in the inverted U structure in two parallel shafts, is equipped with flexible energy storage artificial foot.

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