Patent Application
20140303767
Exemplary embodiments of the present invention relate to a method to operate a production plant.
Production plants in which both people and robots are used are usually constructed such that specific work stations of the production plant are operated by human workers and other work stations of the production plant are operated by robots. The design of the production plant is fixed in this respect; the distribution of work stations to people or robots is fixedly prescribed. Therefore, the robots are usually also fixedly mounted on their respective work stations, such that a flexible reconfiguration of the production plant is not possible and the malfunction of individual units leads to a standstill of the entire plant. Together with the often likewise fixed installation of transport systems, this also leads to a fixed cycle time of the plant, such that the throughput of the plant is not flexibly adjustable to current production requirements.
European patent document EP 1 570 324 B1 discloses a method for dynamic automation in which mobile robots are used, which negotiate different work spaces depending on work steps to be carried out and there co-operate with human workers in that they communicate orders to the human workers with regard to the work steps to be carried out. Such systems have an increased flexibility; the self-moving nature of the robots, however, puts high requirements on their programming, such that even here, changes are difficult to carry out.
Exemplary embodiments of the present invention are directed to a method to operate a production plant that enables a particularly flexible and simple adaptation of the operation of the production plant to different production requirements.
Such a method relates to the operation of a production plant having a plurality of work stations to carry out at least one respective work step. A control system allocated to the production plant is provided to operate the production plant. By means of the control system, human workers or robots are assigned according to the invention according to at least one criterion relating to a production requirement, wherein each worker or robot can be assigned to one or more work stations. In other words, by means of the control system, the respective required number of human workers and robots can be assigned flexibly and according to need to the individual work stations of the production plant in order to operate the production plant optimally to full capacity at each point in time. Due to this flexible assignment, malfunctioning robots or similar can additionally be replaced without problem or their malfunction can, if necessary, be bridged over in the short-term by the use of human workers. Such a method therefore additionally enables an operation of the production plant with a particularly low level of disruption. Due to the variable number of robots and human workers used, an adaptation of the cycle rate of the production plant to possible outside needs is also possible without problem.
It is therefore particularly expedient to use a number of pieces of a product to be manufactured as the criterion relating to the production requirement. Therefore, an occupancy of the production plant that is suited to the load can be ensured at all times.
In a preferred embodiment, the work stations are exclusively occupied with human workers, if the number of pieces to be manufactured is below a first threshold value. Therefore, in the case of small batch production, start-up batch production or in another situation which requires a low number of production pieces, only human workers are used, as the use of robots, which would not be used to full capacity in the case of these numbers of pieces, is uneconomical here. In the case of particularly low numbers of pieces, a single worker can additionally operate several work stations, such that each worker is used optimally to full capacity and is not under-challenged.
If the number of pieces to be manufactured is above the threshold value for the exclusive human occupancy of the production plant, yet below a second threshold value, then both human workers and robots are assigned to the work stations. This can occur very quickly using the control device, such that in the case of a short-term increase of the production capacity, the human workers are supported by robots.
Above the second threshold value, so in the case of a high number of pieces to be manufactured, for example in complete batch operation, all work stations are exclusively occupied by robots, in order to use the advantages of the automation to full capacity and not to over-challenge the human workers.
Therefore, on the whole, human workers and robots are distributed between the work stations in all operation states of the production plant, such that both the workers and the robots are always used optimally to full capacity and no capacities or resources are wasted.
Therein in it is particularly expedient to use robots in the embodiment of the method, which are designed to recognize imminent collisions with objects in their surroundings and to interrupt a motion sequence in the case of such a recognition. This enables a safe co-operation of people and robots in the direct vicinity, for example within a single work station.
Alternatively or additionally to this, an allocated laser scanner can be arranged at each robot, which scans a conical region that surrounds the robot and interrupts a motion sequence of the robot in the case of the introduction of an object or worker into this region. A conflict between robots and human workers can be reliably avoided both by an active collision recognition by the robots and by allocated laser scanners, without safety fences or similar being necessary. Hereby, the space requirement for the robots in the production plant is reduced, wherein at the same time the flexibility of their arrangement is increased. Particular location changes of the robots can be achieved without problem, as no elaborate safety device must be constructed and de-constructed again.
Preferably, a work task is assigned to each robot respectively and a plurality of work tasks is assigned to each human worker respectively in the case of the simultaneous use of robots and human workers. Each human worker can therefore operate, for example, a plurality of robots and supply them with primary products. Such an arrangement uses the particular flexibility of human workers, while the robots, for example, are used for repetitive tasks which are carried out particularly quickly.
For optimal use of the work stations to full capacity, it is furthermore expedient to use respective tools in the work stations that are operable both by human workers and by robots. In a case of a change of occupancy, the work stations thus do not have to be re-adapted to the human workers or the robots, but can continue to be used without a pause. For this purpose, the robots can, for example, be designed to use tools designed for human hands. For this purpose, the manipulators of the robots would then be adapted accordingly. Alternatively, it is possible to use accordingly adapted tools, which, for example, have two handling regions. A first handling region would be ergonomically adapted to the human hand, while a second handling region is designed to interact with the manipulator of a robot.
It is advantageous if at least one work station operated by at least one human worker and/or at least one robot is supplied with primary products and/or material by further human workers. This is above all useful if a work flow is scheduled where certain parts or primary products must be held in stacks and this cannot occur economically in an automated manner.
The invention and its embodiments are described in more detail below by means of the drawing. Here are shown:
A production plant, identified as a whole by 10, which here is designed to manufacture motor vehicle gears, comprises a plurality of work stations 12, which in turn comprise work surfaces 14 and storage containers 16, which are not all identified here for the sake of clarity. Additionally, machine tools, for example presses 18, are allocated to the work stations 12.
In order to be able to operate the production plant 10 optimally in the case of varying loads, a control device is provided that is not depicted in the figures. This receives information about the number of pieces to be produced or number variants of the manufactured products to be produced and subsequently generates instructions for the occupancy of the work stations 12 from this information.
In the situation depicted in
If the requirement for goods to be produced increases, then further human workers 20 can be transferred to take over individual work stations 12 of the production plant 10. Each worker now operates one or two work stations; respectively produced partial products are transferred between the work stations 12.
In the case of a further increasing production requirement, robots 22, as depicted in
In the case of further increasing production requirement, individual human workers 20 can be replaced by further robots 22, until finally in the case of the largest load of the production plant 10, all work stations 12 are occupied by robots 22 in order to achieve a particularly high throughput.
On the whole, the production plant 10 can thus be adapted to all necessary load levels, wherein a change of the configuration of the production plant 10 can occur by means of commands of the control device in real time, in order to adapt the production plant 10 quickly to the fluctuating production requirement.
In order to enable the co-operation between human workers 20 and robots 22 in the tight space of the production plant 10, the robots must have particular safety provisions. For example, the robots 22, as shown in
In order to enable a variation between the use of human workers 20 and robots 22 at the same work stations 12, tools are also used in the work stations 12, preferably exclusively, which are able to be used by both human workers 20 and robots 22. For this purpose, the tools can be adapted such that they have, for example, two different handling regions for human grip and robotic grip. Alternatively, the robots 22 can be adapted such that they can use tools that are designed based on human handling ergonomics. It is herein particularly expedient if the robots 22 have force sensors or toque sensors with which they can determine which force they should exercise on the work piece by means of such tools in order to thus avoid damaging the tools.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/006202 | 12/9/2011 | WO | 00 | 6/4/2014 |
