WO2011156826A1

WO2011156826A1 - Articulated-arm robot

Info

Publication number: WO2011156826A1
Application number: PCT/AT2011/000262
Authority: WO
Inventors: Franz Ehrenleitner
Original assignee: Eb-Invent Gmbh
Priority date: 2010-06-15
Filing date: 2011-06-14
Publication date: 2011-12-22
Also published as: DE102010023789A1; DE112011102003A5; JP2013528503A

Abstract

The invention relates to an articulated-arm robot, comprising a rigid, optionally movable base (5), a base (6) that can be rotated about a preferably vertical axis (2) of the rigid base, a base arm (7) that can be rotated about a preferably horizontal base axis (3), and an end arm (8) that can be moved relative to the base arm. The invention is characterized in that a connecting element (15) is provided between the base arm (7) and the end arm (8). The connecting element is connected to each of the arms (7, 8) about a rotational axis parallel to the base axis (3), namely an arm axis (4) and an end axis (16, 22). In one embodiment, an end arm drive (29) for the motion between the base arm (7) and the end arm (8) acts on an arm guide axis (4') of the connecting element (15).

Description

articulated robot

The invention relates to a articulated robot according to the preamble of claim 1 and the articulated robot shown in FIGS. 94 and 95 of WO 2006/039730 of the applicant.

There are numerous articulated robots, which are constructed similar to the generic robots, reference is made to the following documents: DE 33 24 948: The second, terminal arm is moved by a Gelenkparallelogramm, it is a classic "parallel" articulated robot, such as he will be explained in more detail below.

Applicant's DE 10 2009 034 268: As can be seen from FIG. 4, it is likewise a "parallel" articulated-arm robot, in which, however, additional axes can be operated and load peaks are avoided.

De 20 2007 006 113 U: A classic "serial" articulated robot, as explained in more detail below.

DE 20 2004 017 396 U: A complex device to achieve a special movement of a bottle gripper by means of a link and a four-bar linkage.

DE 20 2004 012 584 U: A classic "parallel" articulated robot with several arm sections whose position is controlled by belt drive.

FR 2 608 737: FIG. 5 shows a device in which the position of the second, terminal arm is determined by an actuator which acts in the upper third of the arm. It is a device that is common in excavators.

DE 30 38 419. corresponding to US 4,396,344: A classic "parallel" robot, as described above in DE 33 24 948. EP 960 982: A crane in which the cabin is movably arranged to allow the driver a better overview. The cab is connected to the crane platform via two serially arranged articulated parallelograms. The drive is via actuators, which act approximately diagonally within the four-bar linkages.

Applicant's WO 2006/039730 discloses a multitude of parallel kinematic arrangements for cranes, robots, lifting tables and others, all of which have in common the use of a so-called 3-2-1 kinematics with so-called pseudo-triplet points, in which the three involved rods or actuators do not " ideal "converge in one point, but just next to each other.

Generic articulated robots have a platform which is rotatable about a vertical axis. On the platform, a horizontal axis, the base axis is arranged, which carries a first arm portion, at the other end parallel to the first axis of rotation turn an axis of rotation, the arm axis is provided, on which a second arm portion engages. At the free end of this second arm cut, in the case of a robot, the actual tool, in the case of a manipulator, which is often similar, arranged a gripping member. The tool or gripping member can usually still be moved with respect to the second arm portion, in particular be rotated about the longitudinal axis of the second arm portion, but variously perform other movements.

A disadvantage of such articulated robots is the inherent need all serial mechanics that each guide and each drive all lying, seen from him to the free end, leadership and drives entrain, carry, accelerate and brake. It comes therefore to extremely poor conditions between payload and dead load, it must be used because of the large mass strong engines, which in turn contribute to increasing the mass and energy requirements, massive bearings must be provided to absorb the dynamic forces occurring with sufficient rigidity to be able to and the like more.

In addition, in the variant referred to as "serial" previously known articulated-arm robot, the longitudinal axes of the first arm portion and the second Armab- Section in the extended state are not aligned with each other, but are offset from each other, whereby moments and torsional stresses are induced in particular in the first, base close, Knickarmabschnitt, which makes further reinforcement and stiffening of all components necessary.

There is a second type of prior art articulated robot, the so-called "parallel" articulated robot, in which the drive and the necessary gear on the axis of rotation between the first and second arm portion (arm axis) is avoided by means of a Gelenkparallelogramms the angle between the second and the first Thus, the servomotor for this axis also comes on the rotatable base, and the entire construction is significantly relieved, moreover, it is possible to lay the two arm axes in a common plane so that their longitudinal axes at a corresponding 180 ° position of the two arm sections are aligned, whereby the above-mentioned harmful bending and torsional moments are largely avoided.

A disadvantage of this construction is that the mobility of the free end of the second arm portion, thus the tool center point, abbreviated TCP, is clearly limited in comparison to the serial articulated robot. In particular, the working area around the vertical axis is lost, even the area below the base axis between the rotatable base and the first arm portion is substantially reduced.

Thus, there is a need for an articulated robot that has a reduced inherent mass, at least in one embodiment with cost-effective components, having a working range that at least comes close to that of the serial articulated arm robots.

According to the invention, this is done by the features stated in the characterizing part of claim 1. In other words, it is provided in a parallel articulated robot instead of the fixed connection of a parallelogram side with the second arm portion a connection via an intermediate element which can take various forms, in particular it may be a gear connection or a framework. By adapted to the particular application training of the intermediate element, it is possible to meet completely different requirements and always get a very easy to build, thus a coming out with light and inexpensive engines articulated robot. When using the framework as an intermediate element is still the waiver of highly accurate and therefore expensive gearbox advantageous.

The invention will be explained in more detail below with reference to the drawing. It shows or show

1 shows a serial articulated robot according to the prior art,

2 shows a parallel articulated robot according to the prior art,

FIGS. 3 to 8, purely schematically, a first embodiment of the invention, FIG. 9 a schematic exploded view of the first embodiment with the forces and moments acting,

10 shows a development of the invention,

1 1 is a schematic exploded view of the development with the forces and moments acting,

FIGS. 12 to 17 show a variant for further development;

Fig. 18 shows an embodiment of the development and

19 to 23 a durchkonstruierte embodiment in various positions in a perspective view.

Fig. 1 shows a serial articulated robot according to the prior art. The robot 1 essentially has a fixed base 5 on which a rotatable base 6 is rotatably mounted about a vertical axis 2. This rotatable base 6 carries, rotatable about a horizontal base axis 3, a base arm 7, at the other end about an also horizontally extending and parallel to the base axis oriented arm axis 4 an end arm 8 is rotatably arranged, which has a tool carrier 9 at its free end. Further provided on the rotatable base 6 is a compensation device 10 which at least partially compensates the static moment loads. To accomplish the rotation of the individual parts about their axes motors are provided, in particular the rotation of the end arm 8 is accomplished about the arm axis 4 by a motor with gear, which is fixed to the base arm 7 in the arm axis 4, so that this arm and its bearing and its drive motor must always move the motor with respect to the arm shaft 4 as a dead load.

It can also be clearly seen from FIG. 1 that the base arm 7 virtually sits "next to" the end arm 8, so that the bending and torsional loading, especially of the base arm 7, already mentioned above, occurs.

For the invention is not decisive, but should not remain unmentioned that the tool holder 9 in turn can perform a variety of movements with respect to the end arm 8 and that, if the device is not used as a working robot but as a manipulator, the tool carrier 9 in the form of a gripper, a magnet, a hook or other device capable of carrying out the respective intended manipulation.

In order to reduce the load on the base arm 7, a so-called parallel articulated robot 1 was developed in the prior art, as can be seen from FIG. 2, which has the structure explained in more detail below, comparable components having the same reference numerals as in FIG. 1 are provided:

In the case of the parallel articulated-arm robot, as shown in FIG. 2, a rotatable base 6 is arranged on a fixed base 5, rotatable about a vertical axis 2. This carries, about a base axis 3 pivotally, the base arm 7, at its upper or free end an arm axis 4 is provided, on which an end arm 8 is pivotally mounted. The end arm 8 is now in the area which faces away from the tool carrier 9, extended and has a bearing about an Armlenkerachse 4 'on which a base link 17 is rotatably mounted, the other, located near the rotary base 6 end, a bearing around a Basislenkerachse 3 ', on which a control link 18 engages. This control link 18 is movable in its orientation with respect to the base arm 7 and in this way effects the quadrilateral formed as an articulated parallelogram, with the vertices 3, 4, 4 ', 3' forming the vertices parallel to one another kinematic chain through which the end arm 8 is pivoted about the arm axis 4. Associated engine is located on the rotatable base 6, so he charged the base arm 7 neither by its weight nor during acceleration by its mass. Despite these advantages, the serial articulated robots have become better established because of the significantly greater range, a comparison of Fig. 1 with Fig. 2 shows that both the accessible angular range of the base arm 7 to the base axis 3 is significantly smaller than the serial robot, as Also, the accessible angular range of the end arm 8 to the arm axis 4. Especially in the mobility upwards and especially on the zenith, thus beyond the extended vertical axis addition, the parallel articulated robot is clearly inferior to the serial.

The Figs. 3 to 8 show now, in a purely schematic manner, the most important elements of an articulated-arm robot according to the invention, with the sake of clarity starting with FIG. 5: for reasons of clarity, the representation of the fixed and rotatable base has also been omitted, as in the representation of the different inclinations of the base arm 7. This is shown in Figs. 3 to 8 are shown only in vertical "normal position" and should serve only as a basis for explaining the mobility of the end arm 8. The base arm 7 is shown as a trapezoid and the end arm 8 as an acute-angled triangle, so that should, but also purely schematically, whose outline is indicated.

In the illustrated embodiment, the connection of these two, for the explanation of the kinematics, as rigid to be viewed components via a base gear 11 and an arm gear 12. The base gear 1 1 is fixed and in particular rotatably connected to the base arm 7, the arm gear 12 fixed and rotatable particular By appropriate storage in a connecting element 15 ensures that the two gears always remain in engagement with each other, so that the center of the arm gear 12 describes a circular arc around the center of the base gear 11. In the practical embodiment, of course, not a whole gear is provided, it is sufficient to provide the required sections designed to fit the two components, the illustration is only the explanation of the kinematics. On the connecting element 15 engages the distance between the two gear axes to an adjusting device which is similar to the parallelogram of the parallel articulated robot as shown in Fig. 2, therefore, the same reference numerals are used here: The base arm 7, the corresponding portion of the connecting element 15th , the base link 17 and the control link 18 form a jointed parallelogram whose angular position is determined by a (not shown) engine in the region of the base axis 3. Due to the change in angle of this articulated parallelogram, as determined by a comparison between Figs. 3 and 8 is easily apparent, there is a much larger change in angle of the end arm 8 with respect to the base arm. 7

It is now readily apparent that by appropriate choice of the individual angles at a randomly assumed as initial position of the individual components and by appropriate selection of the diameter ratios of the gears a good possibility of influencing the achievable for the end arm 8 relative to the base arm 7 angular range about the arm axis. 4 can be achieved. It should be pointed out in this context, however, that the end arm 8 in the construction according to the invention does not perform a pure pivoting movement about the arm axis 4, since the arm gear 12 connected to it rolls on the base gear 1 1.

From Fig. 9, the forces acting on the individual components can be seen. This representation is given here in order to explain an interesting feature of the device according to the invention in more detail:

In the illustration neither the forces caused by weights of the individual components are taken into account nor inertial forces when accelerating or decelerating, it is only the derivation of the forces acting on the TCP force F in the following components set forth. At the end arm 8 of this force is held by the force acting in the bearing of the arm gear 12 upwards, against the force F force F (here is always spoken only of the amount, the orientation is apparent from the drawing) the balance. The associated moment of F about the axis of the arm gear 12 is compensated by the counter torque of the two acting on the arm gear 12 Fz. The connecting element 15 in turn is subject to the forces F and Fz in the bearing of the end axis 16, the rod force Fs, which must always extend in the direction of the base link 17 and ultimately results in the bearing in Armlenkerachse 4 'acting vertical forces F + Fs, and the the force Fz balancing equal drag.

The base arm 7 is thus under the vertical effect of the force F + Fs and acting on the base gear 1 1 moment Fz: Fz, while at its camp about the base axis 3, only the counterforce F + Fs acts. This leads to the surprising conclusion that the force F exerted on the device 1 (as a whole) by a clockwise torque (in the example shown) in the TCP exerts a counterclockwise torque on the base arm 7 in accordance with the force pair Fz: Fz. The torque MArm exerted by the movable platform or by the drive of the base arm 7 keeps the balance of forces.

From the force and torque analysis of FIG. 9, in one embodiment of the invention, a construction can be derived by means of which the torque distribution is optimized, whereby it is possible to further reduce the transmission torques and thus find the way with smaller, lighter and therefore more cost-effective drives In addition, they require less energy during operation, which at present, at times when even production halls are air-conditioned, still helps to reduce the cooling requirements. Such a development is explained in more detail in FIG. 10 and with reference to an example with a belt transmission: On the base arm 7, rotatably connected to the control link 18, a timing sprocket, briefly called just steering wheel 19, stored. Via a connecting element, shown is a belt or a chain 21, the steering wheel 19 is in operative connection with a drive wheel 20, which in turn rotatably connected to the transmission and drive in connection, the opposite side not with the base arm 7, but with the ( not shown) rotatable base 6 is connected. In the illustrated embodiment, the drive wheel 20 half the diameter of the steering wheel 19, so that a translation to the slow of 1: 2 is present. In this way, the drive torque for the movement of the end arm 8 is halved and also transmitted to the base arm 7 a force by which a moment is induced, which counteracts the moment from the tooth flank contact of the gear 11 and this also repeals. It is under these circumstances to a torque derivative in the gear or drives, as in robots according to the prior art in parallel design, but has the advantage that the end arm 8 has a mobility that comes at least close to the serial robots.

The force and torque relationships of the kinematics shown in Fig. 10 are shown in Fig. 11 analogous to the representation of FIG. 9: The ratios in the upper part of the illustration correspond to those of FIG. 9, the induction of the moment by the normal distance between the base axis 3 and the handlebar axis 23, indicated by R2; also visible is the resulting from the tooth forces moment in the arm axis 4 with the active arm Rl.

With knowledge of these relationships, it is now possible in further embodiments of the invention to adapt the force curve or the torque curve to the respective application or, as is usually the case, be designed so that in particular the peaks of the load are minimal. This makes it possible to minimize the power requirement and thus the mass and the costs of the drives as best as possible.

An advantageous embodiment also consists of matching the maximum loads for the drive about the base axis 3 and the drive about the arm axis 4 so that they become the same size, so that it is possible to use identical motor-gear units for both drives. which is advantageous for planning, warehousing and also production costs. On the one hand it is possible to adapt the translation of the sprockets to this goal or to change the position of their axles.

This is with respect to the steering wheel 19, which is non-rotatably connected to the control link 18, thus with respect to the handlebar axis 23 easily possible, if so also from the Gelenkgleichallelogramm a general four-bar linkage, this is regellegstech- - easily manageable. However, this is different with respect to the axis of the drive wheel 20, which must always be the axis 3, because in any other positioning of this axis, the relative position would change with a movement of the base arm 7, which makes problems with the Achsdurchführung one hand, but on the other hand, and This is even more essential, the kinematic relationship with a simultaneous movement of the base arm 7 and the end arm 8 is sensitive.

It is clearly apparent to those skilled in the art that instead of the gears or sprockets, including belts or chain other translations can be provided with linear relationship, such as gear sequences that is to ensure compliance with the correct direction of rotation, of course It has been explained on the basis of the above description, the principle according to the invention to provide a connecting element 15 between the base link 17 and the end arm 8 in order to eliminate the disadvantages inherent in the parallel articulated robot arm of the prior art. It was shown because of the ease of representation and the only minor change in the kinematics between the base arm 7 and end arm 8, the solution with the teeth.

Belt or chain transmission are considered "soft" and thus only partially suitable for robots and manipulators, gears, especially if they are to be highly resilient and yet highly accurate, are costly, it is therefore advisable to choose other fasteners, one thereof is shown in FIGS. 12 to 17, namely an intermediate arm 25 between the base arm 7 and the end arm 8. The kinematics of an articulated robot shown schematically in FIGS. 12 to 17 essentially again have a base arm 7, which does not represent it Base 6 is pivotally mounted about its base axis 3 and a Gelenkparallelogramm, consisting of the pivotable about the respective axes control arm 18, base link 17 and the one leg of the connecting element 15. A third pivot point on the connecting element 15 is pivotable via a connecting shaft 22 with the end arm. 8 connected, and the gears 11, 12 of Fig. 3 to 8 replacing the intermediate arm 25th is hinged at its one end by means of an intermediate axis 24 on the end arm 8, with its other end by means of a connecting axis 22nd on the base arm 7. The excellent mobility that can be achieved by such an arrangement is easily seen from the synopsis of FIGS. 12 to 17. In addition, the fasteners are all cost-effective and precisely producible, beyond also correspondingly lightweight (low-mass) rods, the bearings are standard and also correspond to light, heavy duty and yet cost-effective. Knowing the invention, the best possible positioning of the axes, in particular the control axis 26, the connecting axis 22 and the intermediate axis 24, as well as the choice of the length of the intermediate arm 25 for the intended application area in the field of planar kinematics is easily possible. In addition, by tuning these elements, the required power of the engines and transmissions can be optimized in the desired manner.

It should also be noted that a total swing angle of the end arm 8 of about 240 ° brings about a change in the bar load by a factor of 2, an increase of the total swing angle to 280 ° already by a factor of 3, so that further beyond walking only in exceptional cases makes sense.

In a further embodiment of the invention, which deals in particular with the drive of the control link 18, a four-bar linkage is proposed for the drive instead of the apparent from Fig. 10 linear reduction gear, which has the advantage of light, inexpensive, stable and yet precise components to pass. Such a transmission is shown in FIG. 18 by way of example and purely schematically. The control link 18 is pivoted on the base arm 7 about a steering axis 23, on the Basislenkerachse 3 'attacks not only the base link 17, but also a drive rod 27, which by means of a coupling rod 28 which is hinged to the base axis 3, to As a basis (of the four-bar linkage, not the "rotatable base"), the distance between the handlebar axis 23 and the base axis 3 given on the base arm 7 can be regarded as being sufficient to achieve a transmission to be influenced by the aspect ratios within wide limits to the movement of the base link 17, so that the connecting element 15 and ultimately the end arm 8. All this while simultaneously creating a moment on the base arm 7, the moment on the base arm, by the Forces acting on him from the intermediate arm 25 ago, opposite and can be completely canceled with a suitable choice of the distances and the arrangement of the axles. Whether such a complete cancellation is desired or whether one is content with a weakening of the effect depends on the particular application and is easy for the expert in the field of articulated robots knowing the field of application to make.

FIGS. 19 to 23 show a constructed articulated-arm robot, which essentially corresponds to that of FIGS. 12 to 17, but has yet another special feature.

FIG. 19 shows such an articulated-arm robot with a fixed base 5 and a base 6 which can be rotated about a vertical axis and which has a base axis 3 about which a base arm 7 is pivotable. In the region of the other end of the base arm 7, an arm axis 4 is arranged around which a connecting element 15 is pivotally mounted. The connecting joint 15 has substantially the shape of an elongated triangle, the arm axis 4 is provided in the region of the obtuse angle. At one of the acute angle, a connecting shaft 22 is provided, about which the end arm 8 is pivotally movable.

On the base arm 7, a control axis 26 is arranged in the region of its free arm, on which the intermediate arm 25 engages articulated. This is connected at its other end via an intermediate axis 24 to the end arm 8 articulated. Thus, the connecting element 15 is arranged between the base arm and the end arm 8, so that the high mobility described above with reference to the schematic illustration is achieved.

To complete the kinematics, the connecting element 15 in the region of its second acute angle an Armlenkerachse 4 ', at which the movement of the end arm 8 accomplishing the movement around the base arm 7 four-bar linkage, which differs here to a small extent from the shape of a Gelenkparallelogramms. To complete this four-bar linkage serves the control link 18. The point of attack for the drive for the movement of the two arm sections to each other is now, as well shown in Fig. 18, constructed, the drive rod 27, divided in two for reasons of symmetry, engages the joint of the base link shaft 3 'at. The coupling rod 28, which leads to the Endarmantrieb 29, in turn, can be clearly seen in particular in Fig. 19. The synopsis of FIGS. 19 to 23 shows the extraordinary range of the TCP, which can be achieved by the arrangement according to the invention, it should also be pointed out that the handlebars, levers, rods, etc. used not only extremely inexpensive but also sufficiently stiff for use with articulated robots. In addition, not only because of the enormous mass savings but also because of the special kinematics, the force and torque curves over the individual positions are significantly more balanced and overall noticeably lower than in the prior art, so that the advantages mentioned above come into their own. FIGS. 19 to 23 show yet another embodiment which was not included in the schematic representations of the preceding figures, namely a drive for the base arm 7, which brings about similar advantages as the drive of the end arm 8:

The base arm drive 30 is fixedly provided on the rotatable base 6 but in alignment with the base axis 3. The base arm drive 30 acts on a base coupling 31, which is clearly visible in FIG. At the free end of the base coupling 31 hingedly engages a base friction rod 32 which engages the base arm 7 at a distance from the base axis 3 and at a distance from the arm axis 4 articulated. Thus, this drive forms a four-bar linkage whose vertices are the base axis 3, the axis of the motor 30, the joint axis between the base coupling 31 and the base driving rod 32 and the axis of attack of the base driving rod 32 on the base arm 7.

By choosing suitable distances of these axes from each other is now possible to compensate for the different load of the Basisarmantriebs 30, depending on the position of the base arm 7 at least substantially and thus to much more uniform and especially in their tip greatly reduced loads. In order to clarify these different loads of the base arm drive 30, reference is made to the position of FIG. 21, where the load is only slight, while, for example in the two extreme positions of Fig. 19 and Fig. 23, a large moment load occurs when in this consideration, only the mass of the articulated robot is considered or acting on the TCP with their weight mass. In the knowledge of the labor input, thus if not intended for a universal usability, can be achieved by the appropriate choice of the distances of the four axes mentioned a very substantial reduction of the total mass and energy expenditure.

The invention is not limited to the illustrated and described embodiments, but can be modified variously. Thus, the individual drive types can be virtually freely combined with each other, it can be made differently than in the illustrated embodiment, the shape and design of the arm portions, it can in particular the inventively provided connecting element 15 have a variety of forms, in which in Figs. 19 to 23 shown It combines high rigidity in its longitudinal direction with a high rigidity in the transverse direction, which is also required in working robots. In special cases, the asymmetrical movement of the base arm 7 can be asymmetric on the base arm as explained with reference to FIGS. 19 to 23 acts, be avoided by a doubling with a corresponding reduction of the individual elements, in which case, however, would then be provided on the side of the Endarmantriebs 29, a second drive. The asymmetric force on the base arm 7 represents a much smaller and above all completely manageable problem compared to the advantage obtained equalizing the moment load.

The materials used have long been known to those skilled in the art of articulated robots and require no explanation here. The design of the components, the transmission and the drives is to make the expert in the art with knowledge of the invention also without problems.

Claims

claims:

1. articulated robot with a fixed, optionally movable, base (5), with a about a preferably vertical axis (2) of the fixed base rotatable base (6), with a preferably horizontal base axis (3) rotatable

Base arm (7) and with a movable relative to the base arm end arm (8), characterized in that between the base arm (7) and the end arm (8) is provided a connecting element (15) with the two arms (7, 8) each about the base axis (3) parallel axes of rotation, an arm axis (4) and an end axis (16) is connected.

2. articulated robot according to claim 1, characterized in that a Endarmantrieb for the movement between the base arm (7) and the end arm (8) on an Armlenkerachse (4 ') of the connecting element (15) engages.

3. articulated robot according to claim 1 or 2, characterized in that the base arm (7) has at least one firmly connected to him section of a

Base gear (11), the center of which lies in the arm axis (4), and that the end arm (8) at least one fixedly connected portion of an arm gear (12) whose center lies in the end axis (16), and that comb the two serrations together.

4. articulated robot according to claim 1 or 2, characterized in that the base arm (7) has a control axis (26) and the end arm (8) an intermediate axis (24), and that an intermediate arm (25) is rotatably mounted on both axes.

5. articulated robot according to one of claims 2 to 4, characterized in that the Endarmantrieb on the base arm (7) and in alignment with the base axis (3) is arranged and via a four-bar linkage, preferably a Gelenkparallelogramm (3, 4, 4 ', 3') , on the connecting element (15) attacks.

6. articulated robot according to claim 5, characterized in that the final drive via a coupling rod (28) and an articulated thereon driving rod (27) on the four-bar linkage or Gelenkparallelogramm (3, 4, 4 ', 3') attacks.