CN114981041A

CN114981041A - Method, balancing module and multi-robot system

Info

Publication number: CN114981041A
Application number: CN202180011887.2A
Authority: CN
Inventors: J·M·托罗拉莫斯; D·多西
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2020-01-30
Filing date: 2021-01-29
Publication date: 2022-08-30
Also published as: WO2021152081A1; EP4096872A1; DE102020204710A1

Abstract

The invention relates to the technical field of robots. In particular, the invention relates to a balancing module (20) for a multi-robot system (10), in particular a balancing module (20) for a multi-robot system (10) for collaborative object transportation. Furthermore, the invention relates to a method for operating a balancing module (20) for a multi-robot system (10), to the use of a balancing module (20) and to a robot system (10) having a balancing module (20) according to the invention. Furthermore, the invention relates to a control method for operating a multi-robot system (10).

Description

Method, balancing module and multi-robot system

Technical Field

The invention relates to the technical field of robots. In particular, the invention relates to a balancing module for a multi-robot system, in particular for a coordinated object transport multi-robot system. The invention further relates to a method for operating a balancing module for a multi-robot system, to the use of a balancing module and to a robot system having a balancing module according to the invention. The invention further relates to a control method for operating a multi-robot system.

Background

Autonomous robots, and in particular autonomous transport vehicle robots (also referred to herein as transport robots), are known from the prior art. For example, autonomous robots are used in manufacturing environments in order to transport materials and/or finished products between manufacturing stations and storage facilities. The operation is carried out autonomously, i.e. without direct manual control, but for example as a function of preprogrammed driving behavior, a specified driving route and/or environmental monitoring. Robots are typically unmanned. Since the robot is furthermore usually not stationary, but can be moved to carry out its transport task, it can also be referred to as a vehicle or a vehicle robot.

It is also known to operate a plurality of corresponding robots or transport robots in coordination with one another, in particular for transport tasks. In the specialist field, this is also referred to as the formation of a so-called multi-robot system. For example, advantages arise from the fact that the individual robots have to be constructed to be very powerful and have increased flexibility, since different numbers of robots can be put together depending on the transport task.

The transport is often based on a mechanical connection of the robots to one another. For example, the robots may be coupled at a common load-bearing structure with which the transported object is carried. Such a support structure accordingly forms a mechanical connection and thus a connection structure or connection assembly between the robots. Mechanical forces are thus generated, so that the movements of one robot and the forces associated therewith are also transmitted to the other robot via the connecting structure. Thus, the mechanical coupling may cause the transport robots to have an undesired influence on each other and even cause damage therefrom. The following are particularly problematic: the robot must negotiate different obstacles or experience different road grades (e.g. at a slope).

Disclosure of Invention

Therefore, the following tasks are proposed: the operation of a multi-robot system is improved, the individual robots of which are mechanically or mutually connectable.

The object is solved by the subject matter of the appended independent claims. Advantageous embodiments are given in the dependent claims. The statements and developments described above can also be provided in or applied to the present solution, as long as they are not described or can be clearly seen.

Although at least indirect mechanical connections are maintained between the individual robots of a multi-robot system, it is generally proposed to interconnect the individual robots with a certain gap and/or a defined flexibility. In this way, a defined degree of relative movability between the individual robots may be provided. In other words, despite maintaining the mechanical connection, the robots are mechanically decoupled within defined limits, so that no more all movements and/or forces can be transferred directly from one robot to the other. This is achieved: the reaction of one robot to, for example, a ground tilt that another robot does not experience is not directly transferred to the other robot. In general, the interference influence of one robot is therefore not always completely transferred to another robot. This improves the reliability of operation and reduces the risk of mechanical damage to the robot due to transmitted forces.

In particular, it is proposed to provide mechanical decoupling with respect to a large number of spatial degrees of freedom and to provide corresponding degrees of freedom for the relative mobility. The relative mobility is preferably not realized completely freely here, but rather against or against a purposefully generated counterforce. These thus provide a certain guiding function and dampen the force transmission between the individual robots in a defined manner.

For this purpose, a balancing module is generally proposed, which is preferably arranged in the force path and/or the mechanical connection path between the robots. Preferably, the balancing module is arranged at one of the robots, more precisely at one of the robots in such a way that it connects the robot with a mechanical connection structure (or component) which extends to or is coupled with the other robot. The balancing module preferably provides at least one, preferably a plurality of degrees of freedom with respect to the relative movability between the robot and the connecting structure. Furthermore, the balancing module preferably enables damping of forces transmitted between the connection structure and the robot. In this case, damping is to be understood as meaning that the forces exerted are not transmitted directly to the robot and the respective other units of the connection structure. Instead, the force may at least partially dissipate and/or convert to potential energy that is released only at a later point in time. However, at the point in time of the force application, preferably not all forces reach the respectively connected cell, so that there is a force decay from the point of view of the cell.

If reference is made here to a first and a second robot or a first and a further robot, it goes without saying that the disclosed solution is not limited to this number of robots. In particular, at least three or four robots can also be provided. Furthermore, all robots (but at least more than two) of the system disclosed herein may have a corresponding balancing module. All statements relating to a system with only a first and a second robot apply correspondingly to a system with a larger number of robots.

A first aspect of the invention is a balancing module for a multi-robot system having means for balancing forces. According to a second aspect relating to the first aspect, the balancing module may have a rotating shaft and a bearing, in particular a rolling bearing.

A third aspect of the invention is a method for operating a balancing module having: the forces are measured and the determined forces are balanced.

A fourth aspect of the invention is a multi-robot system having a control or adjustment device for coordinating the movement of at least two robots, wherein forces at the robots are balanced with the control or adjustment device in order to manipulate a common object.

A fifth aspect of the invention is the use of a balancing module for a multi-robot system in a manufacturing process, in particular in the automotive industry.

A sixth aspect of the invention is a robot having a balancing module according to the first or second aspect.

A seventh aspect of the invention is a robot system having at least one balancing module according to the first or second aspect and at least two robots. According to an eighth aspect related thereto, the first robot is an omnidirectional robot and the second robot is a non-omnidirectional robot. Alternatively or additionally, according to a ninth aspect, the first robot is a full robot and the second robot is an incomplete robot. In the seventh to ninth aspects, the robot may have a gripping mechanism, respectively.

Since the robotic system has multiple robots, the terms robotic system and multi-robotic system are used synonymously and interchangeably herein.

All features and functions of the balancing module explained below in connection with the multi-robot system may be applied to the balancing module of the first aspect described above. These features and functions may thus also be claimed as features of the balancing module of the first aspect independently of other features of the multi-robot system below.

In particular, the present invention provides a multi-robot system having: a first autonomous robot, in particular a transport robot, and a second autonomous robot, in particular a transport robot, wherein the first and second robots are connected, in particular mechanically, to each other by a connecting assembly (with which preferably also an object can be carried and/or which is provided for connection with the object); wherein at least one of the robots has a balancing module (e.g. according to the first aspect) by means of which it is coupled to the connecting assembly, wherein the balancing module is arranged for coupling the robot and the connecting assembly to each other in a relatively movable manner and for damping a force transmission between the connecting assembly and the robot.

The robot may be a robot of a robot system according to the second aspect described above. The attenuation may be achieved by means of the balancing module of the first aspect. These forces can be balanced by damping.

The connecting assembly may be a mechanical coupling structure and/or a connecting structure of the type described above. The connection assembly may be one-piece or multi-piece. For example, the connection assembly may consist of a carrier structure or gripper structure at a respective robot coupled to the system (i.e., multi-robot system). If these support structures carry or grip a common object, for example on different sides, a connection or a corresponding connection assembly is produced by the individual structures and objects.

Alternatively, however, the connecting assembly may also comprise, for example, a platform onto which the object is placed. The robots may then be connected directly to the platform, wherein, however, at least one robot is coupled to the platform by means of the described balancing module.

The balancing module may be a module that is structurally integrated, separately manipulatable and/or couplable to the robot as desired. The balancing module may have a smaller size than the robot and/or the connecting assembly. The balancing module may have a cylindrical shape. The balancing module can generally be constructed in multiple parts. The balancing module can face the robot with the first side or can be coupled at the robot with the first side. A second side of the balancing module, which may be remote or remote from the first side, can be coupled to the connecting assembly. In particular, the balancing module may thus be arranged between the connecting assembly and the robot and/or may be couplable at both ends or at both sides with one of the robot and the connecting assembly. Any coupling mentioned herein may correspond to a connection that transmits force.

To achieve the relative movability, a first part of the balancing module may be coupled with the robot and a second part may be coupled with the connecting assembly. The respective parts of the balancing module may be relatively movable with respect to each other. The relative movement can also take place in a guided manner and/or under the action of other elements of the balancing module described below, in particular under the action of elastically deformable elements. For example, the other elements may be positioned between the described portions of the balancing module. In principle, however, it is also possible to couple the parts to one another in an articulated manner and/or to couple the parts to one another by means of a displaceable fluid, in particular a hydraulic fluid, in order to establish the relative movability. In the latter case, these portions may for example delimit a fluid chamber.

As described, attenuation can be achieved by: the forces acting and in particular the forces acting from the connecting assembly and more precisely the correspondingly acting mechanical energy are dissipated and/or converted into other forms of energy (in particular potential energy). The latter is for example the case: as is generally preferred, an elastically deformable element is provided in the balancing module, which element can be deformed as a function of the force or energy applied. However, the means for balancing the forces may effect any of the energy conversions described above. In particular, the means for balancing the force may be elastically deformable or comprise a correspondingly deformable element.

In particular, preferred embodiments provide that the damping of the force transmission comprises the generation of a reaction force against the action of the relative movement. This is based on the idea that the relative movement is usually accompanied by or caused by forces acting on the balancing module. By applying a corresponding counter force acting against the movement action, the forces acting (e.g. when establishing a force balance) can be at least partially compensated and not completely transferred to the respective other connecting assembly and the robot.

In any relative motion considered herein, the following can be taken as a starting point: a stationary (or to a lesser extent moving) robot and a connecting structure that moves relative to it (for example to a greater extent), and in particular forces that originate from the connecting structure. The reaction force generated by the balancing module can accordingly counteract the transmission of force or the action of relative movements proceeding from the connecting assembly.

In particular, it can be provided that the balancing module (and in particular its means for balancing the force) comprises at least one elastically deformable element (for example a spring, in particular a helical spring or a leaf spring) and that the reaction force corresponds to the deformation force of the element to be overcome. The deforming force may be a spring force. In a manner known per se, the deformation force can be generated or act as a function of the length change and against this.

Preferably, a plurality of respective deformable elements are provided. The deformable elements may be oriented differently with respect to each other. For example, the deformable elements may extend in different horizontal spatial directions.

According to a generally preferred variant, the first part of the balancing module described above is at least partially received in the second part of the balancing module, or vice versa. At least one deformable element is preferably positioned between and/or interconnecting the first and second portions. Thus, the parts can be supported against each other by the deformable element over a range of relative movement. In the case of a plurality of deformable elements, the deformable elements are preferably distributed in a horizontal spatial plane, in particular uniformly distributed in the intermediate space between the first and second parts. For example, at least four respective deformable elements can be provided, which are distributed at a spacing of approximately 90 ° relative to one another in respective planes. At least one of the first portion and the second portion may be annular.

According to one embodiment, the balancing module comprises at least one rotary joint, in particular a rolling bearing. With this rotary joint, a relative rotation of the robot and the connecting assembly about a spatial axis, preferably about a vertical spatial axis, can be achieved. It has been shown that with such a rotary joint, the relative offset which often occurs in practice between the robot or the connecting assembly and the robot coupled thereto can be reliably balanced. In addition, the mobility can be improved, since the robot can perform a relative movement about a vertical axis, for example for avoiding obstacles.

The relative rotation about the axis of rotation of the rotation joint (which axis of rotation extends in each case preferably along a vertical spatial axis and/or perpendicular to the ground or the plane of motion of the robot) can take place without damping. In any case, this relative rotation preferably takes place with a smaller damping than the damping of the other relative movements by the balancing module. For example, the rotary joint may not comprise elastically deformable parts and/or may be configured as a conventional rolling bearing.

According to a preferred embodiment, the balancing module enables a relative movement between the robot and the connecting assembly in at least one, at least two and preferably all translational degrees of freedom. In particular, it can be provided that the balancing module at least carries out a relative movement in a horizontal spatial plane, i.e. in which the robot and the connecting assembly are coupled to one another, for example floating, or are supported relative to one another.

All axes and degrees of freedom defined herein may relate to a cartesian space coordinate system. The vertical axis may correspond to the axis along which gravity acts. The other axis may extend horizontally relative to this axis. Translational degrees of freedom may exist along these axes, while rotational degrees of freedom may exist about the respective axes. Preferably, the robot state is discussed here when moving on level ground, wherein, as also explained below, there may also be a different road inclination than on level ground.

Additionally or alternatively, the balancing module may enable relative movement in at least one rotational degree of freedom and preferably at least two rotational degrees of freedom. According to a preferred variant, the balancing module effects a rotation about at least one horizontal axis and preferably about two horizontal axes. The rotation around the horizontal axis is advantageous for balancing different road inclinations below the balancing robot, for example when one of the robots is driving onto a slope while the other remains on a horizontal road. While there may be a free rotation about a vertical spatial axis achieved by the described rotating hinge. While movements with horizontal rotational degrees of freedom can in turn be damped by the balancing module.

A preferred variant provides that the balancing module carries out a relative movement which is damped in all three translational degrees of freedom and about two horizontal spatial axes. While the freedom of rotation achieved by means of the described rotary joint is preferably provided about a vertical spatial axis.

In this case, it can also be provided that the balancing module comprises at least one rotation signal generator, with which the angular position of the rotating joint can be determined. For example, the rotation signal generator can be designed as an encoder. The rotation signal generator can detect, in a sensor-like manner, a relative rotation of a part of the rotating articulation which is coupled to the robot for the joint movement and a part of the articulation which is coupled to the connecting assembly for the joint movement. Based on this, the operation of the at least one robot may also be controlled. For example, it can be deduced therefrom whether one of the robots is traveling too far ahead or whether the respective other robot is falling too far behind. In both cases, an angular position that differs significantly from the predefined neutral position can be detected. Within the scope of the autonomous control and in particular the regulation of at least one of the robots, the latter can then be adapted to the driving operation in order to correct the respective angular deviation.

According to another aspect, the balancing module comprises at least one force sensor. The at least one force sensor is preferably arranged for measuring a force acting between the robot and the connection structure. In particular, the force sensor may measure forces in a horizontal plane. Preferably, a plurality of force sensors are provided in order to measure forces from different horizontal directions, for example along two horizontal spatial axes. In principle, the force sensor may be arranged for measuring the magnitude and/or sign of the force. For example, the force sensor may be a load cell.

According to one variant, at least three, but preferably at least four force sensors are provided, which are distributed in a horizontal plane. In particular, two sensors can be provided for two-dimensional force determination and at least three sensors can be provided for three-dimensional force determination. The force determination may accordingly comprise a direction of force determination, for example by determining a respective two-dimensional or three-dimensional vector. For example, the sensors may be distributed equally spaced from each other, for example 90 ° or 120 ° apart. Two of the sensors may be positioned along an axis corresponding to the robot traveling in a straight line. Whereas two of the sensors (i.e. in the case of four respectively provided force sensors) can be positioned along an axis running orthogonally thereto. In this way, forces acting in the horizontal plane can be reliably detected.

Preferably, the balancing module is also provided for determining the direction of the measured force. For this purpose, for example, the values and/or signs determined by the different force sensors can be evaluated and force vectors can be determined therefrom. This is achieved particularly reliably by the above-described arrangement of at least three or at least four force sensors in a horizontal spatial plane. For example, a force component along a first horizontal spatial axis and a force component along a second horizontal spatial axis can be determined by means of the force sensor in order to determine the described force vector therefrom.

In summary, the use of a force sensor therefore preferably enables the determination of the magnitude and direction of the forces transmitted between the linkage assembly and the robot (in particular the forces transmitted to the robot). This may be, in particular, an initially undamped force contribution which is then at least partially compensated or compensated by the damping capacity of the balancing module.

Another aspect of the invention is preferably provided that the operation of at least one of the robots can be controlled on the basis of the measured forces. For example, the robot can adapt its operation and in particular its driving operation, for example with respect to the selected driving route, driving speed or driving angle. The aim may be to reduce the measured force and in particular to make it zero, respectively. For example, it is thus possible to adjust a steering angle with which the robot can be steered against the direction of the measured force in order to balance the force. The travel speed (and/or travel acceleration) may be selected based on the magnitude of the force.

In principle, at least one of the robots can be controlled and in particular its driving operation can be regulated based primarily or exclusively on the measured forces. This can be done in the described manner such that the measured forces are balanced. This is advantageous because no direct communication between the robots is necessary. For example, the travel operation information does not have to be transmitted between the robots. The driving information may include, in particular, a driving route, a driving speed, a steering angle or an advance adaptation of corresponding parameters.

In particular, it can be provided that at least one or preferably only one robot of the system assumes the guidance role, for example because it obtains information about the route to be traveled. While another robot can assume a following role and follow the lead robot according to the measured forces. This increases the flexibility when putting multiple robot systems together, since the individual robots do not necessarily have to be designed for communication with each other. Instead, the individual robots may actually only communicate with each other indirectly via the measured forces, or more precisely, influence their operation with each other without actually exchanging data or signals. This can also be achieved: at least individual ones of the robots are designed to be completely without communication capability, which reduces costs.

According to a general embodiment, the balancing module is connected to the associated robot via a data transmission interface (wired or wireless). The force measurement or a control signal generated by the controller of the balancing module on the basis of the force measurement can thereby be transmitted to the robot, and in particular to the controller of the robot. An explanation of these controllers is also found below. This has the following advantages: the robot itself need not be arranged to process sensor measurements. This reduces the requirements on the robot, which saves costs and increases the range of applications of the balancing module.

In principle, the robot may be an omnidirectional robot, and in particular a transport robot, which may accordingly be steered in any spatial direction. Preferably, however, at least one non-omnidirectional robot is also provided within the system. Such a combination, which is known in principle from the prior art, is advantageous in terms of a clear controllability within the system and avoidance of redundancy. Preferably, it is provided here that the omnidirectional robot is a guiding robot of the type described above, and the non-omnidirectional robot is a following robot.

Additionally or alternatively, one of the robots may be incomplete, while the other robot may be complete. The latter is preferably again a guiding robot, while another robot can follow the guidance, in particular in the case of force control.

Robots or systems may be used, among other things, for transportation tasks associated with manufacturing processes. In particular, it may relate to manufacturing processes in the automotive industry. Applications in other fields, such as service robots, are also possible. For example, the system can be used as a parking robot system with which a vehicle to be parked can be brought out of or into a parking space.

As already indicated above, each of the robots may comprise a gripping and/or carrying mechanism, which may be an integral part of the connecting assembly, respectively. In this way, the robot can be supported on at least one side of the transported object, and thus indirectly form a mechanical connection (i.e. in particular a force-transmitting or force-guiding connection) to a further robot, which also grips or is supported on the object. The connecting assembly may thus also comprise the object to be transported together with the gripping mechanism.

According to one embodiment, the balancing module can also comprise at least one of the following components:

a sensor for detecting the inclination angle (or tilt angle) of the robot floor. The sensor may be arranged at least one robot, but preferably at each robot, and detects a respective grade angle. The sensor may be an IMU (internal measurement unit).

-a sensor for detecting the weight load acting on the balancing module, or in other words the weight force transferred from the connecting assembly to the balancing module;

-a height adjustment mechanism. In particular, in this regard, the spacing of a first region of the balancing module, to which the connecting assembly can be coupled, from a second region of the balancing module, to which the robot can be coupled, can be varied. Since the balancing module is preferably arranged as a generally preferred aspect at the upper side of the robot and/or is oriented vertically and/or along a vertical spatial axis, a corresponding spacing change results in a height change of the balancing module. More generally, it can also be said that the length varies. The height adjustment mechanism may be mechanical. The height adjustment mechanism may be a toggle mechanism, in particular a double toggle mechanism. The advantage of this mechanism is that robots with different heights can also be connected to each other without the connecting assembly being forcibly adapted.

-a deformable section with which the balancing module is supported at least one of the connecting assembly and the robot. The deformable section is preferably not a deformable element for force compensation as already discussed. Instead, it may relate to a disc-shaped, mat-shaped or plate-shaped element. The deformable section may preferably be made of a coherent and/or homogeneous material. The deformable section may thus be a solid section, for example a rubber plate. The balancing module may stand on the rubber plate or other parts of the balancing module mentioned herein may be supported on the rubber plate. For example, the element or the section can form a foot section of a balancing module, which stands on the foot section, and in particular on a robot. In particular vertically acting vibrations and forces can be balanced and absorbed by the element.

The tilt angle and the weight load can be used to distinguish between measured forces, respectively: whether the force is due to relative movement or height difference or robot's slope travel. In the first-mentioned case, the force can be used, for example, by the control device as a guide preset for controlling one of the robots. However, forces which are not relevant for movement or control can also be effected and measured, in particular in the case of height differences and/or in general in the case of driving on slopes as described above. These forces may also be present even in static conditions (i.e. generally independent of motion), for example due to the tilted position of one of the robots and supporting its own weight by a connection assembly at the other robot. Such force share can be determined based on the inclination angle and the weight load and is not taken as a basis for the motion control.

The invention also relates to a balancing module for a robot of a multi-robot system according to any of the preceding aspects. In general, the balancing module may have any of the features described herein and provide an effect. In particular, the balancing module may comprise at least one first part and at least one second part, wherein the first part may be coupled with the connecting assembly and the second part may be coupled with (in particular may be fixed to) the robot. The portions may be displaceable relative to each other. Furthermore, such displaceability or relative movability may be achieved in case the acting forces are damped, such that the force transmission between the connecting assembly and the robot is damped. For this purpose, any method and device for damping the corresponding forces explained here can be provided.

Also, the invention relates to a robot comprising a balancing module according to any aspect described herein.

Also, the invention relates to a method for operating a robot system, having:

connecting (in particular mechanically) a first robot (in particular a transport robot) and a second robot (in particular a transport robot) to a connecting assembly, wherein the connecting comprises coupling at least one of the robots to the connecting assembly by means of a balancing module; wherein a balancing module is provided for coupling (or connecting) the robot and the connecting assembly to each other in a relatively movable manner and for damping a force transmission between the connecting assembly and the robot.

The method may comprise any further measures and any further features in order to provide all the operating states, interactions and effects described herein. In particular, a robotic system or multi-robotic system according to any aspect described herein may be provided using the method. All statements and developments concerning the features of such a system can also be applied to the same method features.

Furthermore, the invention relates to a method for operating a robot system or a multi-robot system, wherein the robot system is constructed according to any one of the aforementioned aspects, and in particular wherein at least one balancing module of the system comprises at least one force sensor arranged for measuring a force acting between the robot with the balancing module and the connecting structure. The operation of at least one robot of the system may be controlled based on the measured forces. All aspects described above with respect to force measurement and operation control based on force measurement may also be provided in this regard.

In general, it is noted that, with respect to any aspect described herein, operational control of the robot may be implemented by at least a controller (also referred to herein as a control device) of the robot. The controller may provide control functions and/or regulation functions. The controller can obtain the measurement signals generated by the balancing modules and adapt the operation of the respective robot appropriately on the basis thereof. Additionally or alternatively, the module may further comprise a controller. The module may generate a control signal, e.g. based on the measured force, and output it to the robot for controlling the movement of the robot. In particular, these signals can be transmitted to a drive control of the robot, which in turn adjusts the electric power supply to the drive motor of the robot accordingly. The robot itself does not have to process the sensor measurements of the balancing module.

Any controller may include at least one processor and/or at least one memory device. Program instructions that are executable by the processor may be stored on the storage device. With a corresponding implementation, the controller may be enabled to provide the described control and/or regulation functions.

Drawings

Embodiments of the invention are explained below with the aid of the accompanying schematic drawings. Here, features of the same type or the same function may be provided with the same reference numerals across the drawings.

Fig. 1 shows a multi-robot system according to an exemplary first embodiment in a top view.

Fig. 2 shows a variant of the system in fig. 1 in a front view.

Fig. 3 shows a balancing module as it is used in the system in fig. 1 and 2 in a schematic top view.

Fig. 4 shows the balancing module of fig. 3 in a schematic cross-sectional side view in order to explain the internal structure of the balancing module.

Detailed Description

The systems described below each implement the method according to the invention.

In fig. 1, a multi-robot system is shown, which is a robot system 10. The system 10 includes two autonomous traveling robots 12 in the form of transport robots (or mobile robots). System 10 is shown in a top view. The vertical spatial axis Z is accordingly perpendicular to the plane of the page and extends generally in the direction of action of gravity. The other axes of the spatial coordinate system X, Y are indicated as horizontal axes or as extending out of a horizontal spatial plane. The X-axis corresponds to the forward direction of travel, while the Y-axis defines the lateral direction of travel. The location of the coordinate system is also illustrated by fig. 2, in which the system 10 comparable to fig. 1 is shown in a front view.

Referring first to fig. 1 (however, corresponding explanations may also apply to fig. 2), the left-hand robot 12 is an omnidirectional robot (see corresponding hatching of its wheels, which indicates omnidirectional controllability). While the right-hand robot 12 is a non-omnidirectional robot, which is constructed, for example, in the manner of a conventional motor vehicle with a deflectable front axle. The robots 12 are connected to one another by a connecting assembly 14, which is shown merely as a rod by way of example.

It is first considered below that without the balancing module 20 according to the invention, the left-hand robot 12 can accordingly travel in the X and Y directions and rotate about the Z axis. While the right robot 12 can only travel in the X direction and rotate about the Z axis. The same applies to the object 18 carried or moved by the robot 12.

This leads to the following previous problems: with a rigid connection between the robots 12 (especially between generally intact and non-intact robots), the freedom of movement of the entire robotic system 10 is limited during object transport. In particular, the robotic system 10 cannot immediately travel in a sideways direction. The robotic system can only travel forward and backward (in the X direction) and only rotate limitedly (about the Z axis). The robotic system 10 cannot arbitrarily place instantaneous points on the travel plane. Furthermore, due to small control deviations during the course of the movement, undesirable forces may be generated, which may lead to damage of the robot system 10. The balancing module 20 disclosed here not only achieves an expansion of the freedom of movement but also a balancing of the forces occurring.

In the case of fig. 1, the connecting assembly 14 comprises a continuous, one-piece or multi-piece elongated mechanical part 16 extending from the robot 12 to the robot 12, on which a platform covered by a transported object 18 is centrally arranged. The robots 12 are thus connected to each other in a force-transmitting manner by the mechanically rigid parts 16. The object 18 may be a work piece to be transported, a finished product, or an intermediate product. The object may be transported by the system 10 in a manufacturing environment, such as a factory and especially an automotive factory.

The connecting assemblies 14 are connected to the respective robot 12, only exemplarily centrally on the upper side. More precisely, the connecting assembly is mechanically coupled to the robot. This is achieved by the balancing module 20. As can be seen from fig. 2, the balancing module has: a first region 22 (illustratively an outer wall only) for coupling with the component 16 or the connection assembly 14; and a second region 24 (only exemplarily on the underside) for coupling with a respective robot 12.

The balancing modules 20 form flexible coupling elements of the robot 12 and the connecting assembly 14, respectively, and thus also serve to couple the robots 12 to one another at least indirectly. In particular, the balancing module 20 implements the relative movability explained below in order to balance the mutually deviating movement states of the robots 12 with respect to one another. More precisely, the movement of one robot 12 cannot then be transmitted to the full extent to the other robot 12 by means of the connecting assembly 14, but is at least partially compensated or balanced by the relative movability of the balancing module 20. As also explained below, this is preferably achieved when a reaction force (also referred to as reaction force) is applied in order to limit the force transmission of the robots 12 to each other.

In fig. 2, a system 10 similar to fig. 1 is shown in a front view. The only differences are: the connection assembly 14 does not include a continuous member 16 with a platform that may be concealed. Instead, the connecting assembly 14 consists of two gripper units (or gripper mechanisms) 25 (which are each fixed at one of the robots 12). More precisely, the gripping unit 25 is of elongate design and is coupled with a first end to the first region 22 of the respective balancing module 20 (more precisely fixed at the balancing module 20). The gripping unit grips the object 18 at a second end remote from the balancing module 20 (e.g., with a mechanical gripping hand). The connecting assembly 14 of the robot 12, which enables the transmission of forces between the robots, is accordingly formed by two gripper units 14 and the transported object 18.

Without the relative movability and flexibility provided by the balancing module 20 already mentioned, the system shown in fig. 1 and 2 would be limited in its movability. For example, sideways travel, such as that achieved by the left-hand omnidirectional robot 12, is not always possible, as the right-hand robot 12 may tip over. It is also achieved in the manner described by the balancing module 20 that after a lateral start of one robot 12, the corresponding forces are registered in the balancing module 20 of the right-hand robot 12, and then the right-hand robot turns in a suitable manner. Generally, the completely rigid connection of the robot 12 to the connecting assembly 14 is disadvantageous in terms of maneuverability.

Furthermore, the forces of the robots 12 will always be directly and completely transferred to each other, which may lead to damage.

In fig. 3, the balancing module 20 is shown in a top view. The Z-axis is thus perpendicular to the plane of the page and the viewing direction generally corresponds to the viewing direction of fig. 1. The compensation module 20 has a rotating shaft, a bearing housing, a plurality of spring elements 38 and a bearing 30, in particular a rolling bearing. The arrows drawn represent the four directions in which the force can be measured. Not only the direction of the occurring force but also the angle of the occurring force can be measured. To evaluate the force, the value of the force may also be determined. The angle measurement may be detected by the position of the rotating shaft in the balancing module 20. Furthermore, the measurement may be performed by an encoder. The spring element 38 provided can be used to balance the forces occurring (i.e. it can form a means for compensating for the forces). In addition, software may be provided to control the balancing module 20. In summary, the freedom of movement is improved by using the balancing module 20. Furthermore, the forces occurring are balanced. This improves the service life of the individual robots 12 and the entire robotic system 10.

In detail, fig. 3 first shows the first part 30 of the balancing module 20, which is illustratively an intermediate disk. The robot 12 and one of the connecting assembly 14 or the gripper unit 25 may be fixed at this intermediate disc. While a second part 32 of the balancing module 20 in the form of a ring is arranged at the respective other of the connecting assembly 14 or the gripper unit 25 and the robot 12. The connection of the

parts

30, 32 to the respective components can be achieved by suitable mechanical fastening means and/or by means of a clamping connection.

The first part 30 is rotatably mounted about a vertical Z-axis which lies perpendicularly in the plane of the page (see the correspondingly labeled arrow). For this purpose, the first part is received in a rotary bearing 34 (or rotary hinge). The rotary bearing 34 is supported in a retaining ring 36. The rotary bearing is held in the second part 32 by a plurality of spring elements 38, which are not provided with their own reference numerals in each case in fig. 3. The retaining ring 36 may accordingly perform a smaller range of rotational movement than the first portion 30.

The spring elements 38 extend in the horizontal X-Y plane, respectively. Thus, the spring element enables a relative movement of the first portion 30 with respect to the second portion 32 in a horizontal plane and thus at least two translational degrees of freedom (along the X-axis and along the Y-axis). Furthermore, a certain displacement of the

portions

30, 32 relative to each other along the Z-axis (by a corresponding deflection of the spring 38) can thereby be achieved. Preferably, however, this displacement is negligible compared to the vertical support via the elastic plate and its vertical deformability described below. The deflection of the spring 38 in the vertical direction can also be limited in a targeted manner by suitable mounting and in particular vertical support of the retaining ring 36 and the first part 30, for example.

It goes without saying, however, that tilting about the horizontal axis X, Y is also possible as a result of the illustrated elastic support by means of the spring 38.

In contrast, with respect to the vertical Z axis, a substantially free rotation takes place by means of the rotary bearing 34, wherein only the friction forces of the rotary bearing 34 (which is preferably a rolling bearing) have to be overcome. The angular position of the pivot bearing 34 can be detected by a rotation signal generator 37, which is not shown in detail.

Since the spring or means 38 for force compensation is elastically deformable, the relative movement of the

parts

30, 32 is accompanied by a corresponding deformation and therefore a spring force. The deformation and the spring force act counter to the direction of the relative movement. This means that, for example, not all horizontal forces exerted by the outer second part 32 are also transmitted to the inner first part 30. Instead, they are converted into potential energy in part by a corresponding change in length of the spring 38. Thus, from the perspective of the first portion 30, the force transmission is attenuated. Of course, this is also true from the perspective of the second portion 32, when the portion 30 transmits force to the spring 38.

Furthermore, four force sensors S1-S4 are shown, outlined in dashed lines. The respective directions (indicated by means of respective arrows) in which the force can be measured by the respective sensors are also shown. It goes without saying that the force can also be detected in the respectively opposite direction (i.e. with opposite sign). Typically, the sensors S1-S4 are configured to measure not only the magnitude of the applied force, but also its sign. The sensors S1-S4 are positioned such that two sensors are positioned along the X axis and two sensors are positioned along the Y axis. However, other axes can also be selected, but these preferably run orthogonally and/or horizontally to one another. Only one sensor S1-S4 may also be provided along the respective axis.

According to one variant, at least one sensor is therefore provided for each axis and thus at least two sensors S1-S4 are provided in total.

However, with multiple sensors S1-S4 along one axis, higher measurement accuracy may be achieved, such as by averaging corresponding measurements.

Thus, sensors S1-S2 measure force along the X-axis, while sensors S3-S4 measure force along the Y-axis. In this manner, the X and Y components of the force acting on the second portion 32 can be measured. For example, these forces may be transferred from connection assembly 14 to second portion 32. Some of these forces may be damped by deformation of the spring element 38 in the described manner. However, the remaining portion will be transferred onto the first portion 30. Thus, the sensors S1-S4 and the X-Y force components determined therefrom are used to calculate a force vector or determine the primary direction of the applied force. This may be accomplished by transmitting the measurements of the sensors S1-S4 to the control device 100 of the robot 12. In fig. 2, a corresponding control device (controller or control unit) 100 is shown by way of example for a robot 12, and a data connection (which can be implemented wirelessly or by wire) to the balancing module 20 is indicated by a dashed line. Preferably, the further robot 12 also has a corresponding control device 100 with a data connection to the balancing module 20 there.

However, it is particularly advantageous if the balancing module 20 has a control device 100 in order to evaluate all sensor signals detected by the balancing module 20. In particular, the control device (or controller) 100 of the balancing module 20 may generate control signals for the robot 12 carrying the balancing module 20 based on the sensor measurements. These signals can be transmitted to the robot 12 via a data transmission interface that is not separately labeled.

Any of the control devices 100 described herein may be control or regulation apparatus of the type disclosed herein or provide control or regulation functions of the type described herein.

By determining the respective force vector, the robot 12 may obtain information about how the other robot 12 is currently moving or how the connected component 14 is deflected according to the respective movement.

Returning to fig. 2, it is preferably provided according to the invention that the left-hand robot 12 is a guiding robot which has acquired a travel route to be traveled, for example by means of a wireless data connection. While the right-hand robot 12 may not obtain the corresponding route information and may preferably also not communicate directly with the left-hand guiding robot 12 via a data connection. Instead, the right-hand robot can measure the force exerted by the left-hand robot 12 via the connecting assembly 14 and control and preferably adjust its driving behavior on the basis thereof. More precisely, the control device 100 may preferably have a regulating function in order to regulate the driving operation as a function of the forces measured by the sensors S1-S4. The adjustment is preferably carried out in such a way that the steering angle and/or the speed and/or the acceleration are adapted in order to reduce the determined force vector. This is typically done such that the robot 12 moves in the direction of the force vector, wherein the speed and/or acceleration is preferably selected in dependence on the value of the vector. As mentioned, this adjustment function may however also be provided by the balancing module 20 or the control device 100 there, and control signals may be generated and transmitted to the robot 12 in accordance with the adjustments there.

Fig. 4 schematically shows a very greatly simplified structure of the balancing module 20 from fig. 3. The layered structure or corresponding order of the various components is exemplary only. This view corresponds to a cross-sectional view along the Z-Y plane in fig. 3.

Again, a first portion 30 is seen, which is interior, and a second portion 32 is seen, which is exterior. The portion 32 may also provide or correspond to the connection region 22 in fig. 2. Other components arranged between or interacting with the

parts

30, 32, such as the force sensors S1-S4, the rotary bearing 34 and the spring element 38, are not separately shown in fig. 4.

The first portion 30 is connected to a height adjustment mechanism 40. The height adjustment mechanism can be a toggle lever mechanism, in particular a double toggle lever mechanism, and/or an adjustment mechanism in the manner of a scissor lift (scherenlift). In principle, however, the height adjustment mechanism can also be connected to the second part 32 and/or to the two

parts

30, 32.

In addition,

additional sensors

51, 53 are shown. The additional sensor is here a tilt angle sensor 51, with which the inclination of the balancing module 20 and thus of the robot 12 or the road therebelow can be determined. Furthermore, a gravity sensor 53 is shown which measures the acting gravity (i.e. vertical force). This results in advantages in the manner described above, in particular when driving on a slope.

In principle, in addition to the sensors S1-S4, the gravity sensor 53 may also be used to determine the three-dimensional force direction and then to base this direction on the robot control.

Also shown is a deformable plate 42 connected to the first portion 30. The deformable plate forms the support section and includes a second region 24 in fig. 2. It relates to a section that is flexible in a preferably vertical direction in order to be able to absorb the force of gravity. In addition, vibrations can thereby also be damped. Advantageously, this deformable section supports the relative rotation of the first part 30 with respect to the second part 32 also during the slope run, i.e. during the time when one of the robots 12 is located on an inclined road and the other is not or only on a less strongly inclined road.

An alternative layered structure is as follows. The uppermost layer (with reference to the orientation of fig. 4) comprises an interface to the gripping mechanism 25 or the object 18. The second layer positioned therebelow includes force sensors S1-S4 and a counterbalance mechanism or device (spring) 38. Gravity may also be acted upon and/or measured there. Furthermore, gravity can act on the layer lying therebelow. A third layer positioned below the previous layer comprises power electronics and/or a controller and sensing means for detecting the grade angle. A fourth layer positioned below the previous layer comprises height adjustment means. The height adjustment means may comprise a double toggle mechanism and is typically used in robots with different heights. A fifth layer positioned below the previous layer comprises an elastic sheet, for example a rubber sheet. The fifth layer also includes an interface to the robot 12. The rubber plates serve to balance vertical loads and/or loads occurring during ramp travel. In general, a sensor for a slope angle can also be provided, wherein the slope angle is determined, for example, by means of an IMU.

In particular, the exemplary balancing module 20 has the following characteristics and provides the following advantages in terms of flexibility:

-providing balancing means for loads occurring in all longitudinal, transverse, vertical and around longitudinal and transverse directions.

Increased freedom of movement, in particular in terms of rotation about a vertical axis.

-effecting a hill run.

No robot-to-robot communication is required, since indirect communication takes place via force-reversal coupling (force feedback).

In particular, the exemplary balancing module 20 has the following characteristics and provides the following advantages in terms of independence or independence capability:

-providing an integrated sensor device for all required measurement variables, in particular for detecting three-dimensional robot movements, slope angles and object weights;

-providing an integrated control unit which generates and coordinates suitable driving strategies.

In particular, the exemplary balancing module 20 has the following characteristics and provides the following advantages in terms of scalability:

the balancing module 20 is height adjustable. Thereby, robots of different heights can be connected to each other.

The balancing module 20 is robust.

The balancing module 20 can be used independently of the precise robot kinematics and/or its gripping mechanism.

List of reference numerals

10 robot system/multi-robot system

12 robot

14 connecting assembly

16 parts

18 (transporting) object

20 balance module

22 first region

24 second region

25 grabbing unit

30 first part

32 second part

34 rotating bearing

36 retaining ring

37 rotation signal generator

38 device/deformable element/spring

40 height adjusting mechanism

42 deformable plate

51 inclination angle sensor

53 gravity sensor

100 controller/control device

S1-S4 force sensor.

Claims

1. A balancing module (20) for a multi-robot system (10) having means (38) for balancing forces.

2. A robotic system (10) having:

at least one balancing module (20) according to claim 1; and at least two robots (12).

3. The robotic system (10) of claim 2,

characterized in that the robots (12) are an autonomous first robot (12) and an autonomous second robot (12),

wherein the first robot and the second robot (12) are or can be connected to each other by a connecting assembly (14);

wherein one of the robots (12) has the balancing module (20) by which it is coupled to the connecting assembly (14);

wherein the balancing module (20) is provided for coupling the robot (12) and the connecting assembly (14) to one another in a relatively movable manner and for damping a force transmission between the connecting assembly (14) and the robot (12) by means of the device (38) and thereby balancing the forces.

4. The robotic system (10) of claim 2 or 3,

characterized in that the balancing module (20) comprises at least one swivel joint (34) for enabling a relative rotation of the robot (12) and the connecting assembly (14) about a preferably vertical spatial axis (Z),

in particular, the balancing module (20) comprises at least one rotation signal generator (37) with which the angular position of the swivel joint (34) can be determined.

5. The robotic system (10) of any of claims 2-4,

characterized in that the balancing module (20) comprises at least one force sensor (S1-S4) arranged for measuring a force acting between the robot (12) and the connecting structure (14),

in particular, the balancing module (20) is provided for determining the direction of the measured force.

6. The robotic system (10) of claim 5,

characterized in that the operation of at least one robot (12) can be controlled on the basis of measured forces,

in particular, the balancing module (20) is connected to an associated robot (12) via a data transmission interface for transmitting force measurement values or control signals, which are generated by a controller (100) of the balancing module (20) using the force measurement values.

7. The robotic system (10) of any one of claims 2-6,

characterized in that the balancing module (20) further comprises at least one of the following components:

-a sensor (51) for detecting a grade angle of the robot floor;

-a sensor (53) for detecting the gravitational force transferred from the connection assembly (14) onto the balancing module (20);

-a height adjustment mechanism (40).

8. A robot (12) having a balancing module (20) according to claim 1.

9. Use of a balancing module (20) for a robot system (10) in a manufacturing process, in particular in the automotive industry.

10. A method for operating a balancing module (20), the method having:

-measuring the force; and

-balancing the determined forces.

11. A method for a multi-robot system (10) having a control or adjustment device (100) for coordinating the movement of at least two robots (12), wherein forces at the robots (12) are balanced with the control or adjustment device (100) in order to manipulate a common object (18).

12. A method for providing a robotic system (10), the method having:

-connecting the first robot (12) and the second robot (12) with the connecting assembly (14);

wherein the connecting comprises coupling at least one of the robots (12) to the connecting assembly (14) by a balancing module (20); wherein the balancing module (20) is provided for coupling the robot (12) and the connecting assembly (14) to each other in a relatively movable manner and for damping a force transmission between the connecting assembly (14) and the robot (12).