JPS58160087A - Method of determining coordinate of robot arm - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (4) Technical Field of the Invention The invention relates to a robot arm coordinate determination method, and particularly to a five-joint robot arm coordinate determination method.

(H) Technology background Robots are generally used for assembly and transportation of goods, but robots with multi-joint arms are suitable for complex tasks, and they are expensive to use for more advanced precision tasks. A robot equipped with an articulated arm 1 &: with positioning accuracy is available at a low price.

(Q: Prior Art and Problems The teaching-playback (teaching playbag) method is widely used to drive robots.

In other words, after Ohmukai directly holds the tip of the robot arm and positions it at the target position, or remotely controls the tip of the arm using a switch attached to the teaching box, each rjkJw! By repeating the operation of storing the value of the rotation angle detector provided in 8 as the rotation angle of the joint, a data string corresponding to a series of arm movements is created.0 This data string is memorized when the FKO bot arm moves. From the section, the command value is manually applied to the drive circuit of each node. In a robot using such a drive control system, the tip of the arm is correctly positioned at the taught pressure point. However, robots can be used for more advanced tasks, such as arranging and arranging objects in a matrix on a predetermined plane, when the robot is driven by work data programmed using CAD, or by using a television camera. The robot is driven based on the coordinate value detected by the visual U recognition device, and in tasks such as grasping objects, the absolute coordinate system is determined by solving the posture transformation formula determined by the robot's joint configuration. There is a need to convert it to angle data.

By the way, the +1 posture conversion formula includes the arm length of each joint and the joint origin as parameters, and if the parameters include errors, the robot's moving trajectory may differ from the instructed trajectory. Otherwise, it would be inappropriate for the above work.

In other words, assembly derived from robot assembly work! Because there is an I14 difference (error in the inspection of each arm and each joint),
Even if the above-mentioned posture 1 envy equation is solved and the robot is given instructions, the 91-koku movement cannot be used for precision work on a case-by-case basis.

0 OBJECTS OF THE INVENTION The present invention was devised in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a robot arm sitting method that allows the arm to reach a desired position by relatively simple operations. purpose.

(g) Structure and object of the invention According to the present invention, the tip of the robot arm having the first few joints is sequentially positioned at each of n (Y (n≧2) fixed points, and the robot With the tip of the arm positioned at the identification point, the robot arm assumes a plurality of postures, and the rotation angle tube of each related part of the robot arm when forming the plurality of postures. To provide a robot arm position V2 that is detected by a rotation angle calculating means provided at a joint part, and is set to 1 at the detected angle to determine the origin of each joint of the robot arm. Prior to explaining the central and 11th examples of the invention, the basic idea of the present invention will be described.

Figure 1 is a schematic diagram of the robot's construction.A
, ~A is the arm IK, ~ is the joint, and among these, At + As + Ay are the arms AI + A, respectively.
It is possible to rotate any angle around A as the rotation center, and the joints and ~ are each arm A1wAl:As*A4
: Asy It is possible to rotate any angle within the plane formed by A. Arm A.

Coordination thread with the tip A6 fixed to the robot arm
1 (hand coordinate system), and a sub-reference point is set at a point Ak that is perpendicular to the arm At VC and separated from this origin by a rectangular shadow. Joint K is where the H1 sub-measurement reference is set separately in this way, without using the origin as the measurement reference point.

Although there is no change in the position of the tip of the arm At due to the rotation of , the measurement reference point is attached to this joint by the rotation of . Therefore, it is necessary to control the robot's motion taking into account the rotation of joint R1. There are 4.

Here, each parameter of the robot in Figure 1 is as follows.
Define as follows.

&i l arm jJ (1=1°~7) length θ- arm; rJA node Kl (1=1~6) (7) true rotation angle A
θ; 轡; Rotation angle error W of joint Ki based on mechanical setting error of joint Ki ; Position vector A of arm tip, :; Tremor transformation matrix /l; Position coordinate in hand coordinate system Position t1 in hand coordinate system The location of Zakushima in the robot seat system (absolute coordinate system (X6.Y, Zo))
When expressed as r/, it becomes ``ζA,・Sen・几・hAr, At −A D・Met.

However, AT-A1. A,,Aj・A,-! I,, 1°F
J, x (t=x ~ 6) Fimtecv rotation angle e
Since it is a function of (Jllllθ!, θ3.θ4s 01+ ”・), the rotation angle υ origin is a function of θ(Δθ1.Δ0!,
Δθ, Δθ4. Δθ,.

The robot coordinate thread υ reference point position vector F (fltA(B) for the joint angle including 80, ) is expressed by the following formula. (JJ) and the reading value (output value) of the rotary encoder provided at each joint at that time efAθ, the value of δ1 can be obtained from simultaneous equations (2) with δl as an unknown.

Once δ1 is determined, the mechanical setting difference in the chest TFI region can be determined using the second formula (2) and the following formula. If this setting error m0 is known, the arm position kFc(
) 1Δli can be found.

Next, preferred embodiments of the present invention will be described.

FIG. 2 is a diagram of Seiji Sakaki according to an embodiment of the present invention, where B is the robot base, A is the arm, and the arm A, %A,
and the joint is composed of 1 to -. Grasp the displacement detector T with the hand at H. The movement of the spiritual position detector T is converted into an electrical signal by a sensor installed inside the displacement detector G, such as a gold gauge.
2 is a joint angle detection unit, which is provided at the joint K + “” Ka; The joint angle is detected by receiving the output value of a rotary encoder (not shown) that provides the joint angle.

First, the displacement detector G'fr is set at position F4(e) shown in FIG. Detected in this case! +G position ii is FCe 4θ
That is, using formula C21,
is given by (lliji negative t Δ9 t = t rotary encoder next check all * akwt s m position * rl (e) component of vc setting P1z, PtyIP
Since iz* Pazt Pays Pzz'e exists, the above equations (6) and (7) become six simultaneous sword equations, and can be determined for i* of the six unknowns a1 to δ. The position of the detection KG is detected by the first detection part Y and the coordinates are determined based on the position information? It is input to section M. In the coordinate determination N)M, the position information of the detector G and the joint angle 9fh from the joint angle detection unit 2 are obtained.

Find ~δ. Thereafter, the setting error Δe is determined using equations (2) and (5). Then, substitute O + Δ6-, r, : in place of /l) + J in equation (2), perform Mr. Sono's plan, find the true error, and obtain the origin of the correct rotation angle 1 ft. 0 These true The output values δ1 to δ·, AO are sent to the control sC, and the position of the hand H is controlled based on the instruction values θ, to θ. If it is difficult to use the position of the arm tip laterally than the detector GK, the following method may be used.

As shown in FIG. 3, five bins E1 to E arranged on a flat plate (jig) D are sequentially gripped by a hand H of the robot. Coordinate conversion from robot seat system to jig coordinate thread) Let IJ hook B be the position vector of the origin of the jig coordinate thread in the robot seat system, and let the jig coordinate thread of a point on the jig be If the seat 4111 is t, then the position vector of this point on the robot m is IP = try, me, -・-(horn. a. Substitute Nam OQ into the above equation and take the difference between the sides.

The coefficient of 0 becomes lll [9+6= if all tones are unknowns
This becomes a linear phase equation with 15 unknowns. Therefore, some data mustard and a1 can be determined.

The angle is given by the following formula: 0 1 + - C11) (α, β, γ are the attitude angles with respect to the robot coordinate system)
Therefore, by the hand H of the robot, the bottle P of the jig is
, ~P, are sequentially grasped, and the rotation angle of ~ is detected at each joint by a rotary encoder.The joint angle detection unit 2
Detect with. On the other hand, robot coordinate determination fit (In M, rmm angle input from the joint angle detection unit 2 <s) based on the h mm angle et4 t)
The error 4e is determined from ~a. and the true error Δet- is determined by repeated calculations similar to those in the previous embodiment. This error bf) is input to the Fi robot controller C, and the position of the robot arm is controlled based on the separately input instruction value r.

Note that instead of the five bins E1 to E on the jig, any two
Two bottles, for example t'! E+tFJt' can also be used to obtain the unknown numbers δ, ~δ, and the feed difference J.

In Fig. 5 and Fig. 6, the bin EI* E* K valley hand H1-m is fixed, and the output of the rotary encoder provided at 1 to @ is input to the joint angle detector ZK large at the joint at that time. The angle fEfAe is compared and input to the calculation unit F.

holds true. The subscript numbers identify the first and second postures of the arm when Bin E+-EtK Hand H is fixed. In the above equation, Hand H when Hand H is fixed to Bin E+pE snow. Solve the simultaneous equations obtained using the position vectors ff', , and t using arithmetic asp to obtain the solutions a, ~δ, and then use the same method as described above to determine the true 1 difference Δθ.0 Therefore, this error After sending the value e to the robot controller sC, by using this -Q to set the measurement origin of the angle # detector, correct arm position control based on the 4h reading θ becomes possible.

C) Effects of the Invention υ As is clear from the above explanation, the robot arm position determination method according to the present invention can accurately drive the robot arm to any desired position.

[Brief explanation of drawings]

FIG. 1 is a diagram of the construction of a robot, FIG. 2 is a diagram of one embodiment of the present invention, and FIGS. 3 to 6 are diagrams of other embodiments of the present invention.
This is a M-light diagram. A, ~A,; Arm, K, ~; Joint, El~Es
;Fixed point, H: Hand, Y: Displacement detection unit, M: Robot y
Toza! S redundant part, z: joint angle detection part, C: robot side arm part 〇 is also shown in Figure 1Z. Figure 2! +5 Mouth No. 4 Figure ■ 5 Figure YJ□ Figure Ti1i'1' Ii Chojiden 11+l'lt'+/,! Kosho (11 Sγ・I 1.゛1 ma 1 4377th or 31st mountain
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11 Prefecture Kawasaki City Nakah; 11 Zu lI+-1l1111101
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5th Tomi 1: 496 inside Totsu Co., Ltd.

Claims (1)

[Claims] The tip of a robot arm having several joints is
≧2) Sequentially position at each of the fixed points [2. With the tip of the Mukuro robot arm positioned at the fixed point, let the Mukuro robot arm release multiple postures, and form several clusters. Rotation angle t of each joint of the trobot arm at the time - detected by a rotation angle detection means provided at each joint,
A robot arm coordinate law method, characterized in that the origin of each joint of the robot arm is determined based on the detected angle.