CN103862474A - Identification method for robot joint initial parameters - Google Patents

Abstract

The invention relates to an identification method for robot joint initial parameters. The identification method for robot joint initial parameters comprises the steps of: step 1, obtaining a first joint cylindrical coordinate parameter of a joint at a first position; step 2, obtaining a second joint cylindrical coordinate parameter of the joint at a second position; step 3, building mapping between each of the first and second joint cylindrical coordinate parameters and a rectangular coordinate according to the kinematics decoupling characteristics of a robot, and thus obtaining initial parameters, wherein the initial parameters include one or more of an initial radial distance, an initial azimuth angle and an initial joint corner. According to the identification method for robot joint initial parameters, depending on the kinematics decoupling characteristics of the own structure of the robot, the initial parameters which are accurate enough can be obtained; the identification method for robot joint initial parameters can be widely applied to robot job tasks and produce good practical significance, and is outstanding in economic benefit.

Description

The discrimination method of joint of robot initial parameter

Technical field

The present invention relates to robot field, particularly relate to a kind of discrimination method of joint of robot initial parameter.

Background technology

Robot has the joint of multiple serial or parallel connections conventionally, conventionally need to carry out identification to the initial parameter in a certain joint.Take robot palletizer as example, it is generally connected/is composed in parallel by four joints, is widely used in the automatic stacking operation of packed or case goods, has reduced labour intensity, has improved production efficiency.

In actual piling operation process, typical robot palletizer comprises by four the separately-driven waist joints of servomotor, drag articulation, flapping articulation and wrist joints.Wherein, the enlarger of drag articulation and flapping articulation composition parallel form, belongs to cylindrical robot.The angular signal of servomotor feedback motor, can know corresponding joint rotation angle or position by inference according to mechanism driving relation.

Wrist joint is used for grasping goods and moves back and forth at a high speed, and is subject to the effect of goods inertia force.What cause for fear of rigidity deficiency rocks, and robot palletizer adopts hybrid connected structure conventionally.Adopt the robot palletizer structure of series-parallel connection not only to there is the feature that cascaded structure working space is large, and have the large feature of rigidity of parallel-connection structure concurrently, be suitable for high speed piling task.

The actual zero-bit in four joints of robot palletizer is generally determined by the zero-bit of approach switch corresponding to each joint or absolute encoder, often has certain deviation with the layout design of robot palletizer.These deviations are one group for a certain robot and determine numerical value, normally one group of geometric parameter (being initial parameter), and these geometric parameters are input parameters of robot palletizer inverse kinematic, are absolutely necessary.

Often obtain these geometric parameters by the method for actual measurement in practice, but the geometric parameter error of utilizing general survey tool to obtain is larger, can not meet the required precision of inverse kinematic.Therefore, just need the laser interferometer that service precision is higher to carry out the measurement of bulk, to determine accurately the initial parameter of robot palletizer.But laser interferometer cost cost is high, and installation and debugging difficulty, be unfavorable for that actual field deals with problems.

Summary of the invention

The object of this invention is to provide that a kind of cost is low, the discrimination method of the joint of robot initial parameter of being convenient to installation and debugging.

For solving the problems of the technologies described above, as one aspect of the present invention, provide a kind of discrimination method of joint of robot initial parameter, comprising:

Step 1: obtain the first joint circular cylindrical coordinate parameter of joint in the time of primary importance;

Step 2: obtain the second joint circular cylindrical coordinate parameter of joint in the time of the second place;

Step 3: according to the kinematic decoupling characteristic of robot, set up the mapping between the first joint circular cylindrical coordinate parameter and second joint circular cylindrical coordinate parameter and rectangular co-ordinate, thus the initial parameter of obtaining;

Wherein, initial parameter comprises one or more in initial radial distance, initial orientation angle, elemental height and initial joint rotation angle.

Further, step 3 obtains initial radial distance according to following formula:

[R ₀+(p+1)r ₁] ²+[R ₀+(p+1)r ₂] ²-2[R ₀+(p+1)r ₁][R ₀+(p+1)r ₂]cos(θ ₁-θ ₂)=l ²

Wherein, R ₀for initial radial distance; P is joint motions amplification coefficient; r ₁it is the radial distance in the first joint circular cylindrical coordinate parameter; r ₂for the radial distance in second joint circular cylindrical coordinate parameter; θ ₁it is the azimuth in the first joint circular cylindrical coordinate parameter; θ ₂for the azimuth in second joint circular cylindrical coordinate parameter; L is the distance between primary importance and the second place.

Further, step 3 obtains initial orientation angle according to following formula:

cos(θ ₀+θ ₁)[R ₀+(p+1)r ₁]-cos(θ ₀+θ ₂)[R ₀+(p+1)r ₂]=x ₁-x ₂

Wherein, θ ₀initial orientation angle; θ ₁it is the azimuth in the first joint circular cylindrical coordinate parameter; θ ₂for the azimuth in second joint circular cylindrical coordinate parameter; P is joint motions amplification coefficient; r ₁it is the radial distance in the first joint circular cylindrical coordinate parameter; r ₂for the radial distance in second joint circular cylindrical coordinate parameter; x ₁for the x coordinate of primary importance under rectangular co-ordinate; x ₂for the x coordinate of the second place under rectangular co-ordinate; R ₀for initial radial distance.

Further, step 3 obtains elemental height according to following formula:

V ₀=pv ₁+ z ₁or V ₀=pv ₂+ z ₂

Wherein, V ₀for elemental height; P is joint motions amplification coefficient; v ₁it is the height in the first joint circular cylindrical coordinate parameter; v ₂for the height in second joint circular cylindrical coordinate parameter; z ₁for the z coordinate of primary importance under rectangular co-ordinate; z ₂for the z coordinate of the second place under rectangular co-ordinate.

Further, step 3 obtains initial joint rotation angle according to following formula:

${\mathrm{\&alpha;}}_1-{\mathrm{\&theta;}}_1-\frac{\mathrm{\&pi;}}{2}={\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="HDA00002568357200011.png"\; state="\{\{state\}\}">A</figure-callout>}}_0$ Or ${\mathrm{\&alpha;}}_2-{\mathrm{\&theta;}}_2-\frac{\mathrm{\&pi;}}{2}={\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="HDA00002568357200011.png"\; state="\{\{state\}\}">A</figure-callout>}}_0$

Wherein, A0 is initial joint rotation angle; θ ₁it is the azimuth in the first joint circular cylindrical coordinate parameter; θ ₂for the azimuth in second joint circular cylindrical coordinate parameter; α ₁it is the joint rotation angle in the first joint circular cylindrical coordinate parameter; α ₂for the joint rotation angle in second joint circular cylindrical coordinate parameter.

Further, robot comprises waist joint, drag articulation, flapping articulation, wrist translation maintaining body and wrist joint; Waist joint rotates to drive drag articulation, flapping articulation, wrist translation maintaining body and wrist joint to rotate around vertical axis; Wrist translation maintaining body is connected with drag articulation, flapping articulation and wrist joint respectively; The motion of drag articulation in the vertical direction and flapping articulation motion synthesis in the horizontal direction makes wrist joint at horizontal in-plane moving.

Further, the artificial robot palletizer of machine, robot palletizer has the joint of multiple series-parallel connections.

Further, robot comprises that initial parameter is carpal initial parameter for goods being piled up to the wrist joint on pallet; Primary importance and the second place are arranged on pallet.

Further, pallet comprises a side that length is known, and the first end of side is primary importance, and the second end of side is the second place.

Further, discrimination method also comprises step 4: repeatedly repeating step 1, to step 3, to obtain many group initial parameters, after being weighted on average, obtains final initial parameter to many groups initial parameter.

Compared with prior art, the discrimination method of the initial parameter in the present invention, rely on the kinematic decoupling characteristic of robot self structure, can utilize the motion of any two positions (being primary importance and the second place) to implement, distance that can be between these two positions is as input parameter, thereby the initial parameter of obtaining can be widely used in robot manipulating task task, produce good practical significance, remarkable in economical benefits.

Accompanying drawing explanation

Fig. 1 has schematically shown series-parallel connection robot palletizer structure principle chart;

Fig. 2 has schematically shown the identification principle figure mono-of initial parameter;

Fig. 3 has schematically shown the identification principle figure bis-of initial parameter; And

Fig. 4 has schematically shown the identification principle figure tri-of initial parameter.

The specific embodiment

Below in conjunction with accompanying drawing, embodiments of the invention are elaborated, but the multitude of different ways that the present invention can be defined by the claims and cover is implemented.

Robot has the joint of multiple serial or parallel connections conventionally, conventionally need to carry out identification to the initial parameter in a certain joint.

The discrimination method that the invention provides a kind of joint of robot initial parameter, comprising:

Step 1: obtain the first joint circular cylindrical coordinate parameter of joint in the time of primary importance;

Step 2: obtain the second joint circular cylindrical coordinate parameter of joint in the time of the second place;

Step 3: according to the kinematic decoupling characteristic of robot, set up the mapping between the first joint circular cylindrical coordinate parameter and second joint circular cylindrical coordinate parameter and rectangular co-ordinate, thus the initial parameter of obtaining;

Wherein, initial parameter comprises one or more in initial radial distance, initial orientation angle, elemental height and initial joint rotation angle.

By obtaining the first joint circular cylindrical coordinate parameter of a certain joint when the primary importance and the second circular cylindrical coordinate parameter during in the second place, and can be according to the kinematic decoupling characteristic of machine 2, set up the relation between this first second joint circular cylindrical coordinate parameter and this primary importance and the rectangular co-ordinate of the second place, like this, just can pass through these relations, obtain above-mentioned initial parameter.

Compared with prior art, the discrimination method of the initial parameter in the present invention, rely on the kinematic decoupling characteristic of robot self structure, can utilize the motion of any two positions (being primary importance and the second place) to implement, distance that can be between these two positions is as input parameter, thereby obtains enough accurate initial parameters, can be widely used in robot manipulating task task, produce good practical significance, remarkable in economical benefits.

Especially, by this joint, the first joint circular cylindrical coordinate parameter when the primary importance converts rectangular co-ordinate to and can obtain:

$\left\{\begin{array}{c}\cos ({\mathrm{\&theta;}}_0+{\mathrm{\&theta;}}_1)[R_0+(p+1)r_1]=x_1\\ \sin ({\mathrm{\&theta;}}_0+{\mathrm{\&theta;}}_1)[R_0+(p+1)r_1]=y_1\\ V_0-{\mathrm{<figure-callout\; id="1"\; label="pv"\; filenames="HDA00002568357200022.png"\; state="\{\{state\}\}">pv</figure-callout>}}_1={\mathrm{<figure-callout\; id="1"\; label="z"\; filenames="HDA00002568357200022.png"\; state="\{\{state\}\}">z</figure-callout>}}_1\\ {\mathrm{\&alpha;}}_1-A_0-{\mathrm{\&theta;}}_1=\frac{\mathrm{\&pi;}}{2}\end{array}\right.$ Equation group (1)

Second joint circular cylindrical coordinate parameter by this joint when the second place converts rectangular co-ordinate to and can obtain:

$\left\{\begin{array}{c}\cos ({\mathrm{\&theta;}}_0+{\mathrm{\&theta;}}_2)[R_0+(p+1)r_2]=x_2\\ \sin ({\mathrm{\&theta;}}_0+{\mathrm{\&theta;}}_2)[R_0+(p+1)r_2]=y_2\\ V_0-{\mathrm{<figure-callout\; id="2"\; label="pv"\; filenames="HDA00002568357200011.png"\; state="\{\{state\}\}">pv</figure-callout>}}_2={\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="HDA00002568357200011.png"\; state="\{\{state\}\}">z</figure-callout>}}_2\\ {\mathrm{\&alpha;}}_2-A_0-{\mathrm{\&theta;}}_2=\frac{\mathrm{\&pi;}}{2}\end{array}\right.$ Equation group (2)

In above-mentioned equation group (1) and equation group (2):

R ₀for initial radial distance; θ ₀for initial orientation angle; V ₀for elemental height; A ₀for initial joint rotation angle;

P is joint motions amplification coefficient; L is the distance between primary importance and the second place;

R ₁it is the radial distance in the first joint circular cylindrical coordinate parameter; r ₂for the radial distance in second joint circular cylindrical coordinate parameter;

θ ₁it is the azimuth in the first joint circular cylindrical coordinate parameter; θ ₂for the azimuth in second joint circular cylindrical coordinate parameter;

V ₁it is the height in the first joint circular cylindrical coordinate parameter; v ₂for the height in second joint circular cylindrical coordinate parameter;

α ₁it is the joint rotation angle in the first joint circular cylindrical coordinate parameter; α ₂for the joint rotation angle in second joint circular cylindrical coordinate parameter;

X ₁for the x coordinate of primary importance under rectangular co-ordinate; x ₂for the x coordinate of the second place under rectangular co-ordinate;

Y ₁for the y coordinate of primary importance under rectangular co-ordinate; y ₂for the y coordinate of the second place under rectangular co-ordinate;

Z ₁for the z coordinate of primary importance under rectangular co-ordinate; z ₂for the z coordinate of the second place under rectangular co-ordinate.

By the first formula in equation group (1) and the second formula respectively with equation group (2) in the first formula and the second formula subtract each other, can obtain:

Cos (θ ₀+ θ ₁) [R ₀+ (p+1) r ₁]-cos (θ ₀+ θ ₂) R ₀+ (p+1) r ₂]=x ₁-x ₂formula (1)

Sin (θ ₀+ R ₀) [R ₀+ (p+1) r ₁]-sin (θ ₀+ θ ₂) [R ₀+ (p+1) r ₂]=y ₁-y ₂formula (2)

By formula (1) and formula (2) two ends summed square, and arrange and can obtain through triangle formula:

[R ₀+(p+1)r ₁] ²+[R ₀+(p+1)r ₂] ²-2[R ₀+(p+1)r ₂][R ₀+(p+1)r ₂]cos(θ ₁-θ ₂)=l ²

Formula (3)

In above formula, only R ₀for unknown number, therefore, step 3 obtains initial radial distance according to formula (3).

Further, obtaining after initial radial distance, step 3 can also obtain initial orientation angle according to formula (1) or formula (2).

Preferably, step 3 can, according to the 3rd formula in the 3rd formula or equation group (2) in equation group (1), can obtain respectively elemental height:

V ₀=pv ₁+ z ₁or V ₀=pv ₂+ z ₂formula (4)

Preferably, step 3 can, according to the 4th formula in the 4th formula or equation group (2) in equation group (1), can obtain respectively initial joint rotation angle:

${\mathrm{\&alpha;}}_1-{\mathrm{\&theta;}}_1-\frac{\mathrm{\&pi;}}{2}=A_0$ Or ${\mathrm{\&alpha;}}_2-{\mathrm{\&theta;}}_2-\frac{\mathrm{\&pi;}}{2}=A_0$ Formula (5)

Please refer to Fig. 1, wherein, r is radial distance; θ is azimuth; V is height; α is joint rotation angle; X, Z are rectangular axes; O is the intersection point of X-axis and Z axis.Preferably, robot comprises waist joint 1, drag articulation 3, flapping articulation 2, wrist translation maintaining body 4 and wrist joint 5; Waist joint rotates to drive drag articulation, flapping articulation, wrist translation maintaining body and wrist joint to rotate around vertical axis; Wrist translation maintaining body is connected with drag articulation, flapping articulation and wrist joint respectively; The motion of drag articulation in the vertical direction and flapping articulation motion synthesis in the horizontal direction makes wrist joint at horizontal in-plane moving.Especially, the artificial robot palletizer of machine, robot palletizer has the joint of multiple series-parallel connections.Preferably, waist joint 1 is arranged on base 6.

Fig. 2 is the schematic diagram of robot palletizer when with reference to zero-bit, and Fig. 3 is that robot palletizer is in primary importance P ₁time schematic diagram, Fig. 4 is that robot palletizer is positioned at second place P ₂time schematic diagram.Wherein, l ₀refer to robot wrist joint (wrist center) and waist joint 1(waist seat in the time of zero-bit) the distance of central axis.

Preferably, please refer to Fig. 2 to Fig. 4, robot comprises that initial parameter is carpal initial parameter for goods being piled up to the wrist joint on pallet; Primary importance P ₁with second place P ₂be arranged on pallet.Primary importance P ₁with second place P ₂it can be the position between any 2 on pallet.Preferably, pallet comprises a side that length is known, and the first end of side is primary importance, and the second end of side is the second place.Especially, pallet horizontally rotates, and is also known apart from the height on ground.Preferably, pallet is flatly placed.

Preferably, in Fig. 1, establish BC=DE=a, AC=b, CD=BE=d, EF=e, and meet d=pb, the amplification coefficient that e=pa(p is parallel-connection structure).Above-mentioned this tittle is definite geometric constant, can guarantee by Machine Design and processing.

Rely on above-mentioned specific physical dimension, can realize the mobile decoupling of robot palletizer.In the time of the motor rotation of robot waist joint, wrist joint rotates around axle of the plummet; In the time of the motor rotation of robot palletizer drag articulation, wrist joint moves up and down along plummet axis, and carpal displacement be drag articulation displacement p doubly; In the time of the motor rotation of flapping articulation, wrist joint moves forward and backward along horizontal axis, and carpal displacement be flapping articulation displacement p+1 doubly; When carpal motor rotation, adjust the angle of inclination of goods at horizontal plane.

Especially, the primary importance P on pallet ₁with second place P ₂between distance be known, and primary importance P ₁with second place P ₂between line vertical with the X-axis in rectangular coordinate system.

Like this, the x in formula (1) ₁-x ₂=0, the y in formula (2) ₁-y ₂=-l.

Can set up its coordinate system XOY of robot, usually, this coordinate system can be arranged on large ground level.While carrying out identification, can utilize each of controller mobile robot, thus make wrist joint respectively with primary importance P ₁with second place P ₂overlap.The initial parameter of the length dimension recognition machine people that like this, just can utilize pallet in the time of zero-bit.

Preferably, discrimination method also comprises step 4: repeatedly repeating step 1, to step 3, to obtain many group initial parameters, after being weighted on average, obtains final initial parameter to many groups initial parameter.For example, the discrimination method in the present invention, can implement at the short side direction of pallet, solves corresponding first group of initial parameter; Implement with pallet long side direction again, to obtain another group initial parameter, then these two groups of initial parameters are averaged, can further improve identification precision.

Discrimination method in the present invention, is not subject to the physical dimension in each joint and the impact of mismachining tolerance and restriction, and the suction parameter of the robot palletizer inverse kinematic of the kinematic decoupling of series-parallel connection can be provided.This discrimination method does not use externally measured utensil, and precision is not subject to the impact of external factor, can greatly improve the reliability of geometric parameter identification.

The present invention can the initial parameter of identification robot in the time of zero-bit, do not adopted any externally measured sensor, only relies on the input pallet length of side, can once pick out four initial parameters, and polishing while measuring the main motor of starting is on duty by turns.

In real-time identification process, because robot palletizer wrist joint overlaps with pallet two-end-point on one side, may there is small alignment error, cause identification parameter drift-out actual value out, can be by use above-mentioned discrimination method on 2 of the known relative distance of many groups, obtain many group geometric parameters, ask for the mean value of target identification parameter, thereby improve identification precision.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (10)

1. a discrimination method for joint of robot initial parameter, is characterized in that, comprising:

Step 1: obtain the first joint circular cylindrical coordinate parameter of described joint in the time of primary importance;

Step 2: obtain the second joint circular cylindrical coordinate parameter of described joint in the time of the second place;

Step 3: according to the kinematic decoupling characteristic of described robot, set up the mapping between described the first joint circular cylindrical coordinate parameter and second joint circular cylindrical coordinate parameter and rectangular co-ordinate, thereby obtain described initial parameter;

Wherein, described initial parameter comprises one or more in initial radial distance, initial orientation angle, elemental height and initial joint rotation angle.

2. discrimination method according to claim 1, is characterized in that, described step 3 obtains described initial radial distance according to following formula:

[R ₀+(p+1)r ₁] ²+[R ₀+(p+1)r ₂] ²-2[R ₀+(p+1)r ₁][R ₀+(p+1)r ₂]cos(θ ₁-θ ₂)=l ²

Wherein, R ₀for described initial radial distance; P is joint motions amplification coefficient; r ₁for the radial distance in described the first joint circular cylindrical coordinate parameter; r ₂for the radial distance in described second joint circular cylindrical coordinate parameter; θ ₁for the azimuth in described the first joint circular cylindrical coordinate parameter; θ ₂for the azimuth in described second joint circular cylindrical coordinate parameter; L is the distance between described primary importance and the described second place.

3. discrimination method according to claim 2, is characterized in that, described step 3 obtains described initial orientation angle according to following formula:

cos(θ ₀+θ ₁)[R ₀+(p+1)r ₁]-cos(θ ₀+θ ₂)[R ₀+(p+1)r ₂]=x ₁-x ₂

Wherein, θ ₀described initial orientation angle; θ ₁for the azimuth in described the first joint circular cylindrical coordinate parameter; θ ₂for the azimuth in described second joint circular cylindrical coordinate parameter; P is described joint motions amplification coefficient; r ₁for the radial distance in described the first joint circular cylindrical coordinate parameter; r ₂for the radial distance in described second joint circular cylindrical coordinate parameter; x ₁for the x coordinate of described primary importance under rectangular co-ordinate; x ₂for the x coordinate of the described second place under rectangular co-ordinate; R ₀for described initial radial distance.

4. discrimination method according to claim 1, is characterized in that, described step 3 obtains described elemental height according to following formula:

V ₀=pv ₁+z ₁

Or

V ₀=pv ₂+z ₂

Wherein, V ₀for described elemental height; P is joint motions amplification coefficient; v ₁for the height in described the first joint circular cylindrical coordinate parameter; v ₂for the height in described second joint circular cylindrical coordinate parameter; z ₁for the z coordinate of described primary importance under rectangular co-ordinate; z ₂for the z coordinate of the described second place under rectangular co-ordinate.

5. discrimination method according to claim 1, is characterized in that, described step 3 obtains described initial joint rotation angle according to following formula:

${\mathrm{\&alpha;}}_1-{\mathrm{\&theta;}}_1-\frac{\mathrm{\&pi;}}{2}=A_0$

Or

${\mathrm{\&alpha;}}_2-{\mathrm{\&theta;}}_2-\frac{\mathrm{\&pi;}}{2}=A_0$

Wherein, A0 is described initial joint rotation angle; θ ₁for the azimuth in described the first joint circular cylindrical coordinate parameter; θ ₂for the azimuth in described second joint circular cylindrical coordinate parameter; α ₁for the joint rotation angle in described the first joint circular cylindrical coordinate parameter; α ₂for the joint rotation angle in described second joint circular cylindrical coordinate parameter.

6. discrimination method according to claim 1, is characterized in that, described robot comprises waist joint, drag articulation, flapping articulation, wrist translation maintaining body and wrist joint;

Described waist joint rotates to drive described drag articulation, flapping articulation, wrist translation maintaining body and wrist joint to rotate around vertical axis;

Described wrist translation maintaining body is connected with described drag articulation, flapping articulation and wrist joint respectively; The motion of described drag articulation in the vertical direction and described flapping articulation motion synthesis in the horizontal direction make described wrist joint at horizontal in-plane moving.

7. discrimination method according to claim 1, is characterized in that, the artificial robot palletizer of described machine, and described robot palletizer has the joint of multiple series-parallel connections.

8. discrimination method according to claim 7, is characterized in that, described robot comprises that described initial parameter is described carpal initial parameter for goods being piled up to the wrist joint on pallet;

Described primary importance and the described second place are arranged on described pallet.

9. discrimination method according to claim 8, is characterized in that, described pallet comprises a side that length is known, and the first end of described side is described primary importance, and the second end of described side is the described second place.

10. discrimination method according to claim 1, is characterized in that, described discrimination method also comprises step 4:

Repeatedly repeating said steps 1, to step 3, to obtain the described initial parameter of many groups, after being weighted on average, obtains final described initial parameter to described many group initial parameters.

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