Robot

[Detailed Description of the Invention]

[Industrial Application] This invention relates to the structure of the robot in which a position and attitude control with it are possible. [ high and rigidity and ] [ highly precise ] [Description of the Prior Art] The thing of versatility [ structure / for giving desired flexibility to a robot ] already is proposed, and an articulated robot etc. are the typical thing in a rectangular-coordinates type robot, a cylinder coordinates type robot, and it. Although the robot of these versatility has an advantage in each, it has structure which combined a plurality of arms one by one in in-series fundamentally. [Problem(s) to be Solved by the Invention] In To say, the following problems arise as a conclusion of the above-mentioned in-series arm combination in these conventional robots. It is related with the 1st rigidity. That is, since the arm by the side of a tip is supported by the arm by the side of a end face (floor), as for it, a remarkable burden is placed on the arm by the side of a end face, and it is low [ the rigidity ]. Conversely, if it says, in order to improve the rigidity as the whole robot, it is a situation where the arm by the side of a end face and the dynamic structure of a joint must be enlarged or complicated. The 2nd problem is related with control accuracy. As mentioned above, especially by the conventional robot, since the rigidity by the side of the end face falls easily, even if it raises the drive accuracy in each joint, there is a limit in the control accuracy of a position or a posture in an end effector. Since the control error in each arm or a joint is accumulated one by one toward the tip side, there is also a situation that an error will become large, near an end effector. Since the 3rd problem does not have the same structure of each arm or a joint, it is a problem that the manufacturing cost as the whole robot becomes high. The 4th problem is the controllable problem. That is, the structure of each arm or a joint is not the same, and also since the symmetry of the geometric locating position is low, the conventional robot cannot perform control using the symmetry between arms. [Objects of the Invention] This invention is [ in / have intention of solution of the above-mentioned problem in conventional technology, and / a robot's structure ] ■. Making it possible to improve rigidity, even if it does not use the big member or a complicated structure of size, and ■ Highly precise control is enabled, ■ Reduce a manufacturing cost, ■ Aim at enabling control using symmetry by improving the geometric symmetry of structure. [Means for solving problem] First, the robot according to claim 1 has the following. having the composition corresponding to the object of above-mentioned ■ and ■ -- (a) -- an arm of N book supported via the 1st surface-of-a-sphere joint by N supporting points (N-5 or 6) of having been distributed in two dimensions or in three dimensions, (b) An end effector maintenance object combined with each of the above-mentioned arm via The and surface-of-a-sphere joint of 2 while a predetermined end effector was attached, (C) N actuators which are combined with each of the above-mentioned arm and make the length of each arm in the section between the above-mentioned 1st and 2nd surface-of-a-sphere joint expand and contract individually. And the position and posture of the above-mentioned end effector are changed by driving each of the above-mentioned actuator. The robot according to claim 2 corresponds to the object of above-mentioned ■~■, each structure of said arm is substantially the same, and each of said actuator has the same structure substantially. The robot according to claim 3 corresponds to the object of ■~■, and each of said 1st surface-of-a-sphere joint exists in the position equivalent to each vertex of a regular polygon, Let each locating position of the 2nd above-mentioned surface-of-a-sphere joint in the above-mentioned end effector maintenance object be a vertex position of a regular polygon or a regular polyhedron. [Function] By being combined with each arm, if an end effector maintenance object makes each arm expand and contract by an actuator, it can change the position and posture. Since the end effector is attached to this maintenance object, the position and posture of an end effector also change with these. By this robot, the end effector maintenance object is supported by each arm in parallel. For this reason, a burden is placed on a specific member and that rigidity does not fall. Since the control error in each arm is not accumulated, highly precise control is possible. This robot's manufacturing cost can be reduced by making the same substantially structure of each actuator which drives these each arm and it. The geometric symmetry as the whole robot improves by making symmetrical geometrically each arrangement of the 1st and the 2nd spherical bearing. As a result, it becomes controllable [ using symmetry ]. The "surface-of-a-sphere joint" in this invention is a general term for various kinds of mechanisms which can change a direction in three dimensions, such as spherical bearing and a surface-of-a-sphere link. [Example] <A, mechanistic composition > Drawing 1 is a notional perspective view of robot 1 which is one example of this invention. This robot 1 has the structure hung from ceiling surface 2, and comprises laser torch LT as an end effector as a laser-beam-cutting robot which turns a laser beam to a work (not shown) and irradiates with it. The details of each part are as follows. It is attached to each vertex position of the right hexagon assumed on ceiling surface 2 in 48~4 f of six spherical bearing. And a total of 6 arm 5a~5f is inserted in 48~4f of each spherical bearing, respectively. These arm 5a~5f, it is constituted by the ball screw axis and has the same structure mutually. [ above 48~4 f of spherical bearing ], actuator 3a~3f for a ball screw drive is connected with this arm 5a~5f, respectively. 33~3 f of these actuators serve as an electric cylinder which has the same structure mutually, and the details are shown in Drawing 2 about one actuator 3a. In Drawing 2, actuator 3a has stator 22 fixed to the inner wall of housing 21. Rotor spindle 23 in the air is provided in the position which counters this stator 22, and permanent magnet 24 is being fixed to the circumference of rotor spindle 23. And the principal part of direct drive type servo motor M is constituted by such combination. Ball Nut 25 is attached to rotor spindle 23 at the same axle, and ball screw axis 5a is screwed in this Nut 25. As shown in Drawing 3 as an expanded sectional view, 5 s of flat faces are formed in the peripheral face of ball screw axis 5a. And flat face 31S (Drawing 3) corresponding to 5 s of this flat face is formed in boss's 31 (Drawing 2) inner wall provided in an open lower end part of housing 21. When these flat faces 5s and 31s carry out spline engagement, rotation of ball screw axis 5a is prevented. Therefore, if servo motor M1 is driven, Nut 25 will also rotate and ball screw axis (arm) 5a will move in the direction of an axis (±A) by it. On the other hand, boss's 31 central part is extended tubular, and is being inserted and fixed to inside 33 of spherical bearing 4a. And ball screw axis 5a is extended down the ceiling surface 2 through the hollow part of this inside 33. Outer wheel 34 of spherical bearing 4a is being fixed to bore 35 drilled in ceiling surface 2. For this reason, ball screw axis 5a and actuator 3a can change that posture free by using central point B of spherical bearing 4a as a fulcrum. The posture shown by the imaginary line all over the 2nd figure shows the example of such posture change. Hollow shaft 26 is being fixed to pole Nut 25 in actuator 3a by the upper part. This shaft 26 rotates with rotation of Nut 25, and that rotation angle is read by rotary encoder 28. Braking mechanism 27 is allocated in the outside of shaft 26, and it can do [ stopping rotation of shaft 26 (therefore, Nut 25) if needed, or ]. Omission prevention member 3o is attached to the upper end part of ball screw axis 5a, and the whole ball screw axis 5a falls from ceiling surface 2 by malfunction. It returns to Drawing 1 and the lower end is combined with end effector maintenance object 10 6 arm (ball screw axis) 5a~5f supported and driven by such composition. although this combination is made via surface-of-a-sphere link 6a~6f -- these Spherical sink 6 -- it has a~6 f of the same structures mutually. As shown in Drawing 4, surface-of-a-sphere link 6a (6b~6f) can attach link ball 41 to the lower end of arm 5a (5b~5f), and it can be freely rotated in three dimensions by this link ball 41 within holder 42. For this reason, as an arrow shows all over the 4th figure, arm 5a (5b~5f) can change that posture in three dimensions to holder 42. As shown in Drawing 1, in end effector maintenance object 10, 68~6 f of these surface-of-a-sphere links are attached to each peak of right 8 face pieces. It is prescribed by the combination of frame 7 and arms 5a, 5c, and 5e of these right 8 face pieces are arms 5b to each vertex of the upper surface side triangle in each vertex of the undersurface side triangle again. 5d and 5f are combined, respectively. the [ therefore, ] -- as shown inA [ 5 ] figure as a schematic plan view, arm 5a~5f will have combined between a~4 f left-handed-rotation arrangement and the surface-of-a-sphere link 6a~6f left-handed-rotation arrangement on spherical bearing 4 end effector maintenance object 10 by the side of a ceiling surface, respectively. It is because arranging surface-of-a-sphere link 6a~6f every one on the upper surface side triangle and the undersurface side triangle can prevent especially the mutual interference of 58~5 f of arms effectively in the operation mentioned below. It is not indispensable that at least one side should just have this flexibility, and gives both sides this flexibility among spherical bearing 4a~4f and 68~6 f of surface-of-a-sphere links of Drawing 1 about the rotation flexibility (roll rotation) of the circumference of the axis of 58~5 f of ball screw axes. End effector tie-down plate 8 is being fixed to the undersurface side triangle portion (Drawing 1) of end effector maintenance object 10. Laser torch LT is being fixed in the center of this tie-down plate 8, and that pipe point is suitable in the direction perpendicular to tie-down plate 8. Supply of the laser beam to laser torch LT is performed by optical fiber bunch 9. <B, electric composition > Drawing 6 is a block diagram of robot's 1 control system. Controller 100 has CPU and a memory and outputs a laser oscillation control signal to laser oscillator]01. The laser beam from laser oscillator 101 is supplied to laser torch LT via optical fiber bunch 9. On the other hand, controller 100 generates robot's 1 operation instruction signal, and gives it to motor driver 102. Motor driver 102 supplies electric power to motor M in each actuator 3a~3f according to the operation instruction signal, and rotates each motor M. The output pulse of each encoder 28 in each actuator 3a~3f is taken into encoder output pulse processing circuit 103, and after being changed into a rotation angle indication signal in this circuit 103, it is given to controller 100. Although not illustrated, control to braking mechanism 27 in each actuator 3a~3f is performed similarly. Although this robot's 1 composition is new, that control method in particular is not limited and can apply various control methods, such as playback control and NC control. To C1 principle of operation and characteristic > Next, this robot's 1 principle of operation is described. 6 flexibility is required in order to change the position and posture of an end effector arbitrarily as everyone knows. And since it is being fixed to end effector maintenance object 10, the end effector (laser torch LT) in this example can change the position and posture of an end effector arbitrarily, if 6 flexibility is given to this maintenance object]O. As mentioned already, the length of 58~5 f of arms between spherical bearing 4B~4f and 68~6 f of surface-of-a-sphere links can be individually expanded by robot] and contracted by driving actuator 3a~3f individually. and the thing established for a total of 6 sets of such drive mechanisms -- end effector maintenance object 10 (therefore, laser torch LT) -- the -- it can be arbitrary and can change various postures. In this example, since redundant flexibility is not given, the drive quantity of 33~3 f of each actuator corresponding to the position and posture of laser torch LT becomes settled uniquely. Drawings 7 and 8 show typically the example of a position and posture change. [ such ] The black dot in a figure shows notionally spherical bearing 4a~4f by the side of a ceiling surface, and white round * shows 68~6 f of surface-of-a-sphere links on end effector maintenance object 10. In order that a straight line may understand easily by showing arm 5a~5f, the auxiliary mouth is given to each part. As shown also in these figures, each elasticity of arm 5a~5f can bring about a position and posture change of laser torch LT because joint part 4a~4f and each 6a~6f are surface-of-a-sphere joint. And it can ask for the conversion type expressing the relation between the position and posture of laser torch LT, and the amount of elasticity of 58~5 f of each arm by the usual technique known for the field of robotic control engineering. Specifically, the following analyses can be conducted. First, the center of a right hexagon of specifying a spherical bearing 4a~4f position in Drawing 1 is made into the starting point, and the XYZ absolute coordinate system which took the Z-axis for XY axis perpendicularly in the level surface again is considered. the [ and ] -- the [ corresponding toA / 5 / figure ] -- a surface-of-a-sphere A bearing 4a~4f position vector [ in / onB / 5 / figure and / this absolute coordinate system ] -- Q It is referred to as -06. it can set to this absolute coordinate system -- a surface-of-a-sphere link is carried out. Surface-of-a-sphere link 6a~6f position vector in local coordinate system E fixed to laser torch LT (a , b, C) (i= 1~6) It is considered as -(1). From internal arrangement of end effector maintenance object 10 being fixed, The vector of (1) type is a constant vector. On the other hand, the position and posture of laser torch LT seen from the absolute coordinate system are expressed by coordinates matrix:. However, alpha, beta, and gamma are direction cosines and both "Nes" is constants which become settled so that the square sum of the element of each line and the square sum of the element of each sequence may become "1' in an upper left side of matrix of the above (2) 3x3 partial matrix. At this time, it is vector P. Each ingredient of (1-1~6): P and - (X, Y6.Z) .. (3)1j] 1 -- of -- it can write like. However, a mouth is a portion which is not used as a calculation result. Therefore, thing for which (4) types are calculated when the position and posture of laser torch LT are specified by xrY, z-alpha, beta, and gamma, Ingredient x, y, and z, i.e., each Law 1, of each vector P, of (3) types 1 The absolute coordinate of 68~6 f of] side Li Truck is known. length of 58~5 f of each arm in the section between spherical bearing 4a~4f and surface-of-a-sphere link 6a~6f 11~p6 [ and ] -- 1, 2 =, -=;J, and -100 -- I 2 (i-1~6) ... if referred to as (5), it can be made to take the position and posture which were specified about laser torch LT. A position and the transformation matrix to minute change of a posture, It may ask for the Jacobian of f+ (+-1~e), P, and (i= 1~6) using (5) types. ]

being characteristic in this robot 1 -- each arm 5 -- a~5 f or since it is combined with end effector maintenance object 10 in parallel, it is the point that load does not concentrate on a specific arm. When laser torch LT is leaned, the load of 53~5 f of each arm becomes imbalanced, but the difference is small Hungry comparatively. namely, end effector maintenance object 10 -- six arms 5 -- it is supported by a~5 f by the assignment ratio of the always equivalent or state near it. For this reason, sufficient rigidity is securable even if it does not enlarge the size or structure of each member. The locational error of laser torch LT is comparable as each of each amount error of elasticity in arm 5a~5f, and it does not become the sum of each arm 5a~5f error. The position accuracy of eye this t2 and laser torch LT improves remarkably. That rigidity is also high as mentioned above contributes to the improvement in accuracy. On the other hand, the manufacturing cost as the whole robot also falls by making the same mutually 68~6 f of actuators, and each arm 5a~5f composition. Since the replacement parts by failure etc. can also be communalized, maintenance cost is also reduced. By robot 1, it has the rotation symmetry nature of every 120' around the main vertical axis 2 (Drawing 1) by having arranged 48~4 f of each spherical bearing on the vertex of a right hexagon, and arranging each surface-of-a-sphere link 6a~6f on each vertex of right 8 face pieces. Therefore, when one locus is given about laser-Chi LT, If it asks for the control data corresponding to the locus, the control data about other loci which only 120' xn made rotate the locus concerned to the circumference of the Z-axis (n-1*2, ...) can be easily obtained by replacing the drive quantity for every arm cyclically. <D, other Examples > (1) With the composition shown in Drawing 9, end effector maintenance object 10A was made into the right hexagon, and the surface-of-a-sphere link is attached to the vertex. In this case, as compared with robot 1 of Drawing 1, the interference region between arms has the advantage that the three-dimensional size of end effector maintenance object 10A becomes [ law ] small to some extent in To. Geometric symmetry also further increases. (2) In Drawing 10, combination of spherical bearing and an actuator is made into 5 sets, and the arm also has only five. And on end effector maintenance object]alumnus, equilateral pentagon arrangement is carried out and the spherical bearing by the side of a ceiling surface is also considering the surface-of-a-sphere link as equilateral pentagon arrangement. This is reflecting the following situations. That is, when an end effector has the rotation symmetry nature of the circumference of the axis like a laser torch, only a pitch and Yeoh are important among the posture 3 element, and control of a roll angle is unnecessary. For this reason, 5 flexibility is sufficient for Hurry up in many cases, and it Response to it, and is also making the drive system only into 5 sets. [ of an end effector ] [ the position and attitude control ] SeveralN of Ham generally needed in order to define the position and posture of an end effector in this invention, and an actuator is 5 or 6. When control of a roll angle is unnecessary as mentioned above, in the case of N-6, 1 set of them can be considered to be redundant flexibility, and can also be used for it. It is preferred to arrange the spherical bearing by the side of the point supporting [ arm ] on the vertex of a regular polygon, and to arrange the surface-of-a-sphere link by the side of an end effector on the vertex of a regular polygon or a regular polyhedron, as mentioned already. (3) In the example of Drawing 11, every two pieces which adjoin among six surface-of-a-sphere links of Drawing 9 were substantially summarized in the same position, and arrange them. However, two arms extended from one position are to be made [ changing the posture independently or ]. Since the position and posture will become settled uniquely if the position of three (there is nothing on the same straight line) points defined on it is appointed, such simplification of end effector maintenance object 10C is also attained. (4) It is not necessary to necessarily support each arm in a ceiling surface, and may support it at various supporting points, such as a ceiling surface, a wall surface, and a floor. Drawing 12 shows the example supported from the both sides of ceiling surface 51 and wall surface 52. However, since three-dimensional control becomes impossible when each supporting point is on a straight line, the surface-of-a-sphere joint which supports each arm is distributed in two dimensions or in three dimensions, and must be fixed. (5) In the example of Drawing 13, electric cylinder 56 is provided in the middle of arm 55 which attaches surface-of-a-sphere link 54 to ceiling surface 53, and is extended. Although it is also possible to constitute this invention using such an arm, since there are situations, like an excessive burden is placed on the upper part of that the large stroke of electric cylinder 56 cannot be taken or arm 55 in this arrangement, arrangement of each example mentioned already is preferred. (6) it is not necessary to make into a problem what to use as that end effector by the robot of this invention -- it can use as various kinds of robots, such as * handling robot, a welding robot, a robot assembler. A supporting point may be set up on the structure which does not need to set up on a fixing structure thing, for example, runs a rail top. The arm may have a flection. [Effect of the Invention] As explained above, according to the invention according to claim 1, a burden is not placed on a specific part in order to support an end effector maintenance object in parallel with 5 or six arms. For this reason, a robot's rigidity can be improved even if it does not use a large-sized or complicated structure. The control error in each arm does not accumulate, but since the rigidity as the whole robot is also high, highly precise control is attained. In the invention of Claim 2, since structure of each arm or each actuator is further made the same substantially, the manufacturing cost falls. Since the geometric symmetry of the position which supports each arm in the invention of Claim 3, and the connecting position of each arm on an end effector maintenance object is improved, control using symmetry is possible.

[Brief Description of the Drawings]

Drawings 1 are a typical perspective view of the robot which is one example of this invention, and Drawing 2, The sectional view of the actuator and spherical bearing in an example, and Drawing 3, The sectional view and Drawing 4 showing the spline engaging of clutch between the actuator of Drawing 2, and an arm (ball screw axis), the [ the perspective view of the surface-of-a-sphere link used in an example, and ] -- the [ the schematic plan view showing arm arrangement / in / inA / 5 / figure / an example /, and ] -- the block diagram of a control system for which the explanatory view of coordinate conversion [ in / inB / 5 / figure / an example ] and Drawing 6 are used in the robot of an example, A figure and Drawing 9 to Drawing 13 where Drawings 7 and 8 illustrate that operation about the robot of an example is a figure showing the modification of this invention. 1 ... robot, 2 ... a ceiling surface and 3a~3f ... Actuator (electric cylinder), 4a~4f [ ... End effector maintenance object, ] ... 58~5f of spherical bearing (1st surface-of-a-sphere joint) ... An arm (ball screw axis), 6a~6f ... A surface-of-a-sphere link (2nd surface-of-a-sphere joint), ]O