The present invention relates to a system and method for controlling operation of a group comprising a cigarette maker, a cigarette packing machine and a buffer.

Smoking articles, such as cigarettes, are typically manufactured and packaged by means of groups of highly automated units comprising a cigarette maker, wherein smoking articles are assembled starting from raw materials such as tobacco cut filler, wrapping paper, filter segments and tipping paper, and a packing machine, wherein bundles of smoking articles are collated and packaged into containers, such as hinge lid containers.

In such groups of automated units, a buffer is typically provided between the cigarette maker and the cigarette packing machine. The buffer acts as a reservoir of formed smoking articles to minimise the dependency between the cigarette maker and the packing machine.

Several operating parameters of cigarette maker, buffer and cigarette packing machine need to be pre-set in view of specific production requirements. Whenever one such group is operated to produce cigarettes with different characteristics, for example, cigarettes of a different brand or design, it is necessary to set certain operating parameters to different specific values to ensure stable operation of the group.

The cigarette maker and the cigarette packing machine run at independently variable production speeds. In general, the cigarette maker and the cigarette packing machine generally run at different predetermined production speeds, and so the buffer filling level varies over time.

If the buffer gets full, the cigarette maker needs to be stopped and is only restarted when the buffer filling level falls below a first maker threshold value (cigarette maker starting limit). In order to reduce the occurrences of cigarette maker stops, it has been proposed to reduce the production speed of the cigarette maker when the buffer filling level exceeds a second maker threshold value (cigarette maker reduced speed limit), which is typically lower than the first maker threshold value. Such reduced speed is a pre-set parameter of the cigarette maker.

When the buffer filling level decreases back to a value below the second maker threshold value, the production speed of the cigarette maker can be increased again. However, in order to limit the frequency with which cigarette maker speed shifts occur, it has been proposed that the production speed of the cigarette maker be increased only when the buffer filling level falls below the second maker threshold value by a predetermined amount (cigarette maker hysteresis width).

On the other hand, when the buffer gets empty, the cigarette packing machine needs to be stopped and is only restarted when the buffer filling level reaches a first packer threshold value (cigarette packing machine starting limit). In order to reduce the occurrences of cigarette packing machine stops, it has further been proposed to reduce the production speed of the cigarette packing machine when the buffer filling level falls below a second packer threshold value (cigarette packing machine reduced speed limit), which is typically greater than the first packer threshold value. Such reduced cigarette packing machine speed is a pre-set parameter of the cigarette packing machine.

When the buffer filling level increases back to a value above the second packer threshold value, the production speed of the cigarette packer can be increased again. However, in order to limit the frequency with which cigarette packing machine speed shifts occur, it has been proposed that the production speed of the cigarette packing machine be increased only when the buffer filling level exceeds the second maker threshold value by a predetermined amount (cigarette packing machine hysteresis width).

Whenever the cigarette maker is stopped, some cigarettes are rejected. Similarly, whenever the cigarette packing machine is stopped, some cigarette packages are rejected. Further to the conditions identified above, other reasons such as machine breakdown, lack of one or more of the starting materials, etc. may cause the cigarette maker or the cigarette packing machine to have to be stopped. In addition, during production, some cigarettes or cigarette packages or both may also be rejected if they are found to not meet certain quality requirements. All these rejects represent a loss, and so it would be desirable to limit the occurrences of cigarette maker and cigarette packing machine stops.

In even more general terms, it would be desirable to increase the productivity and overall efficiency of a group comprising a cigarette maker, a cigarette packing machine and a buffer. In practice, the overall efficiency of one such group may be assessed as the 'uptime', that is, the ratio between the total number of cigarettes actually produced over a given time and the number of cigarettes that could theoretically be produced if the group constantly ran at design speed for the same time.

Therefore, it would be desirable to provide a method of controlling operation of a group comprising a cigarette maker, a cigarette packing machine and a buffer interposed between the cigarette maker and the cigarette packing machine, such that the overall efficiency of the group is increased. Further, it would be desirable to provide a method of controlling operation of one such group such that the total production (for example, expressed in terms of the total number of cigarettes produced and packed over a given time) is increased, for example by reducing the number of rejects during production. Further, it would be desirable to provide a system capable of implementing one such method.

According to an aspect of the invention, there is provided a method of controlling operation of a group comprising a cigarette maker, a cigarette packing machine and a buffer, wherein, with respect to a conveying direction, the cigarette maker is upstream of the buffer and the cigarette packing machine is downstream of the buffer, the group being configured such that operation of the cigarette maker and of the cigarette packing machine depends on a filling level of the buffer. The method comprises: setting at least one operating parameter of the group at a starting value, the parameter correlating an operation state of the cigarette maker or the cigarette packing machine with the filling level of the buffer; and operating the group for a predetermined first cycle time based on the at least one operating parameter. Further, the method comprises determining an operating efficiency of the cigarette maker over the first cycle time; determining an operating efficiency of the cigarette packing machine over the first cycle time; determining a group comparative efficiency as the ratio between the operating efficiency of the cigarette maker and the operating efficiency of the cigarette packing machine. In addition, the method comprises, at the end of the first cycle time, resetting the at least one operating parameter at an updated value depending on the group comparative efficiency.

According to a further aspect of the present invention, there is provided a system comprising: a first group comprising a cigarette maker, a cigarette packing machine and a buffer, wherein, with respect to a conveying direction, the cigarette maker is upstream of the buffer and the cigarette packing machine is downstream of the buffer, such that operation of the cigarette maker and of the cigarette packing machine depends on a filling level of the buffer. Further, the system comprises first sensor means for detecting a filling level of the buffer, an actual production output of the cigarette maker and an actual production output of the cigarette packing machine in the first group; and a control unit operatively connected with any one of the cigarette maker, cigarette packing machine, buffer or any combination thereof in the first group, and configured for managing operation of the first group in accordance with a method as set out above.

It shall be appreciated that any features described with reference to one aspect of the present invention are equally applicable to any other aspect of the invention.

In contrast to known methods of operating a group of automated units comprising a cigarette maker, a buffer and a cigarette packing machine, according to the present invention at least one of the parameters defining how the various automated units in the group are operatively correlated - that is, in particular, defining how an operating state of the cigarette maker and the cigarette packer is impacted by the filling level of the buffer - is adaptively adjusted as a function of measured values of cigarette maker efficiency and cigarette packing machine efficiency.

The inventors have found that, by managing operation of one such group by a method in accordance with the present invention, the overall productivity and efficiency of the group can be advantageously increased, in terms of both total cigarette production and of uptime. In general, the impact of unequal full production speeds of cigarette maker and cigarette packing machine can be advantageously reduced.

Further, the inventors have found that methods according to the present invention may be further optimized to account for deliberate, routine stops of the group - like, for example, stops for cleaning purposes - such that the resulting apparent variations in the group efficiency do not impact the adaptive control logic underlying the methods of the present invention.

The term "cigarette maker" is used throughout the specification to refer to an automated unit which is configured to receive tobacco, filter rods, wrapper paper and tipping paper as raw materials and to form from said raw materials a plurality of filter cigarettes. The cigarette maker can generally be run at a full production speed and at a reduced production speed. Thus, the cigarette maker can be in one of several different operation states (for example, full speed, reduced speed, stop). By "production speed" or "production rate" reference is made throughout the specification to the number of goods (in the case of the cigarette maker, the number of cigarettes) produced during a given period of time. By way of example, the production speed or production rate may be measured and expressed in terms of cigarettes/hour.

Several makes and models of cigarette makers will be known to the skilled person. For example, one such automated unit is PROTOS PM 100 (from Hauni Maschinenbau AG, Germany).

The term "cigarette packing machine" is used throughout the specification to refer to an automated unit which is configured to receive a filter cigarettes and packaging material and to collate and package bundles of filter cigarettes to form packs of filter cigarettes. The cigarette packing machine can generally be run at a full production speed and at a reduced production speed. Thus, the cigarette packing machine can be in one of several different operation states (for example, full speed, reduced speed, stop). In the case of the cigarette packing machine, the production speed or production rate generally refers to the number of goods, that is, the number of packs produced during a given period of time. Each pack contains a predetermined number of cigarettes, for example 20 cigarettes/pack. Thus, the production speed or rate of the cigarette packing machine may also conveniently be expressed as the number of cigarettes that are packed during a given period of time, so that it is easier to compare and correlate the production speed of the cigarette packing machine with the production speed of the cigarette maker. Accordingly, in the following, the production speed of the cigarette packing machine will also be measured and expressed in terms of cigarettes/hour.

Several makes and models of cigarette packing machines will be known to the skilled person. For example, one such automated unit is F550 (from Focke GmbH, Germany).

The term "buffer" is used throughout the specification to refer to an automated unit configured for receiving cigarettes formed by the cigarette maker and transfer them to the cigarette packing machine.

Several makes and models of buffers will be known to the skilled person. One such automated unit is CAPRICORN (from ITM, The Netherlands). In the present specification, reference is made to one or more "operating parameter of the group" as a parameter setting a dependency between an operation state of the cigarette maker or the cigarette packing machine with the filling level of the buffer. In practice, an "operating parameter of the group" corresponds to a given filling level of the buffer at which an operating state of one of the cigarette maker and the cigarette packing machine or both is configured to change.

One such operating parameter is, for example, the "cigarette maker reduced speed limit", that is the filling level of the buffer above which the production speed of the cigarette maker is decreased from the full production speed to the reduced production speed.

Other such operating parameters of the group include:

the "cigarette maker starting limit", that is the filling level of the buffer below which the cigarette maker is restarted after a stop caused by the buffer filling up;

the "cigarette maker hysteresis width, that is the difference between the cigarette maker reduced speed limit and the filling level of the buffer below which the production speed of the cigarette maker is increased back from the reduced production speed to the full production speed; the "cigarette packing machine reduced speed limit", that is the filling level of the buffer below which the production speed of the cigarette packing machine is decreased from the full production speed to the reduced production speed;

the "cigarette packing machine starting limit", that is the filling level of the buffer above which the cigarette packing machine is restarted after a stop caused by the buffer becoming empty; and the "cigarette packing machine hysteresis width", that is the difference between the cigarette packing machine reduced speed limit and the filling level of the buffer above which the production speed of the cigarette packing machine is increased back from the reduced production speed to the full production speed. Figure 1 qualitatively illustrates how these parameters may relate to one another.

The term "operating efficiency of the cigarette maker" is used throughout the present specification to refer to the ratio between the actual production output of the maker, that is the number of cigarettes actually produced during the scheduled production time, and the theoretical production output. The theoretical production output is calculated as the product of the scheduled production time by the full production speed of the cigarette maker.

, . . actual maker production output ,,, , maker operating efficiency = ( 1 )

{scheduled production time) -(maker full production speed)

The term "operating efficiency of the cigarette packing machine" is used throughout the present specification to refer to the ratio between the actual production output of the maker, that is the number of cigarettes actually packed during the schedule production time, and the theoretical production output. The theoretical production output is calculated as the product of the scheduled production time by the full production speed of the cigarette packing machine.

, . . actual packer production output

packer operating efficiency = (2)

{scheduled production time) - packer full production speed)

Methods in accordance with the present invention are for controlling operation of a group of automated units comprising a cigarette maker, a cigarette packing machine and a buffer, wherein, with respect to a conveying direction, the cigarette maker is upstream of the buffer and the cigarette packing machine is downstream of the buffer. One such group is configured such that operation of the cigarette maker and of the cigarette packing machine depends on a filling level of the buffer according to a predetermined logic. In particular, an operating state of the cigarette maker or the cigarette packing machine or both is impacted by a filling level of the buffer. By way of example, as the filling level of the buffer varies from 0 percent to 100 percent, the cigarette maker or the cigarette packing machine is typically configured to run at a full production speed or to run at a reduced production speed to stop.

In a method according to the present invention, at least one operating parameter of the group, the parameter defining a correlation between an operation state of the cigarette maker or the cigarette packing machine and the filling level of the buffer, is set at a starting value, and the group is operated for a predetermined first cycle time based on the at least one operating parameter.

Further, the method comprises determining an operating efficiency of the cigarette maker over the first cycle time; determining an operating efficiency of the cigarette packing machine over the first cycle time; and determining a group comparative efficiency as the ratio between the operating efficiency of the cigarette maker and the operating efficiency of the cigarette packing machine. At the end of the first cycle time, the at least one parameter is reset at an updated value depending on the determined group comparative efficiency.

Preferably, the actual production output of the cigarette maker and the actual production output of the cigarette packing machine are monitored continuously, such that it is advantageously possible to determine the efficiency of the cigarette maker and the efficiency of the cigarette packing machine at any given time during the first cycle time. As an alternative, the actual production output of the cigarette packing machine may be detected at predetermined intervals during the first cycle time, so that only discrete values of the efficiency of the cigarette maker and the efficiency of the cigarette packing machine at predetermined moments during the first cycle time may be determined. The at least one parameter is reset at an updated value based on the group comparative efficiency as determined at the end of the first cycle time, and so the actual production output of the cigarette maker and of the cigarette packing machine are detected at least at the end of the first cycle time.

The at least one parameter is reset at an updated value depending on the group comparative efficiency as determined at the end of the first cycle time.

Thus, in methods according to the present invention, the quality and extent of the operative correlation between the cigarette maker and the buffer, or between the cigarette packing machine and the buffer, or both are revised during operation of the group. This is advantageous in that, although the group is initially operated with the at least one parameter set at a starting value that has been specifically selected for a given brand or make of cigarette and, therefore, for a given combination of raw materials and production requirements, the same parameter is adaptively adjusted in view of variations in the efficiency of the automated units involved in the production process.

Preferably, the at least one operating parameter is selected from the group consisting of cigarette maker starting limit, cigarette maker reduced speed limit, cigarette maker hysteresis width, cigarette packing machine starting limit, cigarette packing machine reduced speed limit, cigarette packing machine hysteresis width. The inventors have observed that adaptively adjusting in accordance with the logic underlying the invention one or more of these parameters that set clear correlations between an operation state of the cigarette maker or cigarette packing machine and the filling level of the buffer, it is easy to enhance the productivity and efficiency of the group as a whole.

Preferably, the step of resetting the value of the at least one operating parameter comprises determining a corrected value of the at least one operating parameter as a function of the group comparative efficiency at the end of the first cycle time.

In some embodiments, if the corrected value of the at least one parameter is in the range from a lower boundary value of the at least one parameter to an upper boundary value of the at least one parameter, the at least one operating parameter is reset at the corrected value. Otherwise, if the corrected value of the at least one parameter is less than the lower boundary value of the at least one parameter or greater than the upper boundary value of the at least one parameter, the at least one operating parameter is reset at the starting value.

In other embodiments, if the corrected value of the at least one parameter is from a lower boundary value of the at least one parameter to an upper boundary value of the at least one parameter, the at least one operating parameter is reset at the corrected value. If the corrected value of the at least one parameter is less than the lower boundary value of the at least one parameter, the at least one operating parameter is reset at the lower boundary value of the at least one parameter. If the corrected value of the at least one parameter is greater than the upper boundary value of the at least one parameter, the at least one operating parameter is reset at the upper boundary value of the at least one parameter.

Thus, it is advantageously possible to check that the at least one operating parameter falls within an acceptable range. This has to do not only with inherent constraints relating to the nature of the group (for example, the filling level of the buffer can only be from 0 percent to 100 percent), but also with the fact that certain relationships between the various operating parameters are preferably preserved. By way of example, the cigarette maker reduced speed limit is preferably lower than the cigarette maker starting limit. Further, this is advantageous in that the boundary values can be optimised such that implementation of methods according to the present invention yield most stable increases of production.

Preferably, the step of determining a corrected value of the at least one operating parameter comprises multiplying a base line value of the at least one operating parameter by a factor substantially equal to the group comparative efficiency at the end of the first cycle time, or by the inverse thereof.

The cigarette maker starting limit defines the filling level of the buffer below which the cigarette maker is restarted after a stop caused by the buffer filling up. If the full production speed of the cigarette maker is greater than the full production speed of the cigarette packing machine (that is, a bottle neck region is near the 100 percent buffer filling level), and if the cigarette maker efficiency stays constant and the cigarette packing efficiency increases, the occurrence of stops of the cigarette maker due to the buffer becoming full will decrease. A similar behaviour is expected if the full production speed of the cigarette packing machine is greater than the full production speed of the cigarette maker (that is, where a bottle neck region is near the 0 percent buffer filling level) and if the cigarette maker efficiency stays constant and the cigarette packing efficiency increases.

However, in the latter case, the occurrence of stops of the cigarette maker will be reduced by a slightly greater extent. In practice, the amount of buffer content that needs to be consumed by the cigarette packing machine before the cigarette maker can be started again can be decreased. Thus, the cigarette maker starting limit can be regarded as directly proportional to the efficiency of the packing machine. At the same time, the cigarette maker starting limit can be regarded as inversely proportional to the efficiency of the cigarette maker. Thus, it can be considered that:

maker starting limit∞ (packing machine efficiency / maker efficiency) (3)

The cigarette maker reduced speed limit defines the filling level of the buffer above which the production speed of the cigarette maker is decreased from the full production speed to the reduced production speed. If the full production speed of the cigarette maker is greater than the full production speed of the cigarette packing machine (that is, a bottle neck region is near the 100 percent buffer filling level), and if the cigarette maker efficiency stays constant and the cigarette packing efficiency increases, the occurrence of stops of the cigarette maker due to the buffer becoming full will decrease, because the packing machine is essentially consuming more. On the other hand, if the full production speed of the cigarette packing machine is greater than the full production speed of the cigarette maker (that is, where a bottle neck region is near the 0 percent buffer filling level), and if the cigarette maker efficiency stays constant and the cigarette packing efficiency increases, the frequency with which the buffer becomes full will decrease by a larger extent. Thus, the filling level range within which the cigarette maker runs at reduced speed may be decreased. This results in an additional filling level range wherein the cigarette maker can run at full production speed, which is expected to yield an increase in the production.

Accordingly, the cigarette maker reduced speed limit can be regarded as directly proportional to the efficiency of the packing machine. At the same time, the cigarette maker reduced speed limit can be regarded as inversely proportional to the efficiency of the cigarette maker. Thus, it can be considered that: maker reduced speed limit∞ (packing machine efficiency / maker efficiency) (4)

The cigarette maker hysteresis width defines the difference between the filling level of the buffer above which the production speed of the cigarette maker is decreased from the full production speed to the reduced production speed (that is, the cigarette maker reduced speed limit) and the filling level of the buffer below which the production speed of the cigarette maker is increased back from the reduced production speed to the full production speed. If the full production speed of the cigarette maker is greater than the full production speed of the cigarette packing machine (that is, a bottle neck region is near the 100 percent buffer filling level), and if the cigarette maker efficiency stays constant and the cigarette packing machine efficiency increases, the likelihood that the cigarette maker needs to be stopped due to the buffer becoming full will increase slightly. However, if the full production speed of the cigarette packing machine is greater than the full production speed of the cigarette maker (that is, where a bottle neck region is near the 0 percent buffer filling level), and if the cigarette maker efficiency stays the same and the cigarette packing machine efficiency increases, the likelihood of cigarette packing machine stops due to the buffer becoming empty will increase. Thus, under such circumstances, the cigarette maker hysteresis width may be decreased with a view to limit the impact of the creation of a bottle neck.

Accordingly, the cigarette maker hysteresis width can be regarded as inversely proportional to the efficiency of the cigarette packing machine. At the same time, the cigarette maker hysteresis width can be regarded as being directly proportional to the efficiency of the cigarette maker. Thus, it can be considered that: maker hysteresis width∞ (maker efficiency / packing machine efficiency) (5)

The cigarette packing machine starting limit defines the filling level of the buffer above which the cigarette packing machine is restarted after a stop caused by the buffer becoming empty. If the full production speed of the cigarette maker is greater than the full production speed of the cigarette packing machine (that is, a bottle neck region is near the 100 percent buffer filling level), and if the cigarette packing machine efficiency stays constant and the cigarette maker efficiency increases, the occurrence of cigarette packing machine stops due to the buffer becoming empty will decrease. Thus, in order to enhance the production, the cigarette packing machine starting limit could be decreased, so as to have a wider range of buffer filling level values at which the cigarette packing machine is effectively in a productive state. However, if the full production speed of the cigarette packing machine is greater than the full production speed of the cigarette maker, and if the cigarette packing machine efficiency stays the same and the cigarette maker efficiency increases, the occurrence of cigarette packing machine stops due to the buffer becoming empty will decrease. Thus, the cigarette packing machine starting limit should be lowered by a lesser amount. Accordingly, the cigarette packing machine starting limit can be regarded as being inversely proportional to the efficiency of the cigarette maker.

If the full production speed of the cigarette maker is greater than the full production speed of the cigarette packing machine, if the efficiency of the packing machine increases while the efficiency of the cigarette maker stays constant, the likelihood that the buffer becomes empty will also increase. Therefore, the cigarette packing machine starting limit should be increased to improve productivity. On the other hand, if the full production speed of the cigarette packing machine is greater than the full production speed of the cigarette maker, and if the efficiency of the packing machine increases while the efficiency of the cigarette maker stays the same, an empty buffer condition will occur much more frequently than a full buffer condition. Thus, in one such case, the cigarette packing machine starting limit should be increased by a greater extent. Accordingly, the cigarette packing machine starting limit can be regarded as being directly proportional to the efficiency of the cigarette packing machine. Thus, it can be considered that: packing machine starting limit∞ (packing machine efficiency / maker efficiency) (6) The cigarette packing machine reduced speed limit defines the filling level of the buffer below which the production speed of the cigarette packing machine is decreased from the full production speed to the reduced production speed. If the full production speed of the cigarette maker is greater than the full production speed of the cigarette packing machine, and if the efficiency of the packing machine increases while the efficiency of the cigarette maker stays the same, the occurrence of stops of the cigarette packing machine will increase because the cigarette packing machine is producing more. Under such circumstances, the cigarette packing machine reduced speed limit could be advantageously increased. On the other hand, if the full production speed of the cigarette packing machine is greater than the full production speed of the cigarette maker, and if the efficiency of the packing machine increases while the efficiency of the cigarette maker stays the same, the cigarette packing machine reduced speed limit should be much higher, since it is more likely that the buffer will become empty. Accordingly, the cigarette packing machine reduced speed limit can be regarded as being directly proportional to the efficiency of the cigarette packing machine.

If the full production speed of the cigarette maker is greater than the full production speed of the cigarette packing machine, if the efficiency of the cigarette maker increases while the efficiency of the cigarette packing machine stays the same, it will be less likely that the buffer becomes empty. Thus, under such circumstances, the cigarette packing machine reduced speed limit could be lowered. On the other hand, if the full production speed of the cigarette packing machine is greater than the full production speed of the cigarette maker, the reduction in the cigarette packing machine reduced speed limit should be slightly less significant, because the bottle neck region is near the 0 percent buffer filling level. Thus, it can be considered that: packing machine reduced speed limit∞ (packing machine efficiency / maker efficiency) (7)

The cigarette packing machine hysteresis width defines the difference between the filling level of the buffer below which the production speed of the cigarette packing machine is decreased from the full production speed to the reduced production speed (that is, the cigarette packing machine reduced speed limit) and the filling level of the buffer above which the production speed of the cigarette packing machine is increased back from the reduced production speed to the full production speed. If the full production speed of the cigarette maker is greater than the full production speed of the cigarette packing machine, the buffer filling level will be closer to 100 for most of the production time. If the efficiency of the cigarette maker increases while the efficiency of the cigarette packing machine stays constant, the number of stops of the cigarette packing machine will increase. On the other hand, if the full production speed of the cigarette packing machine is greater than the full production speed of the cigarette maker, an increased efficiency of the packing machine will result in a much higher number of stops of the packing machine. To counter this effect, the cigarette packing machine hysteresis width can be increased, such that the impact of stops of the cigarette packing machine is reduced. Therefore, the cigarette packing machine hysteresis width can be regarded as being directly proportional to the efficiency of the cigarette packing machine.

If the full production speed of the cigarette maker is greater than the full production speed of the cigarette packing machine, if the efficiency of the cigarette packing machine stays the same and the efficiency of the cigarette maker increases, the likelihood that the buffer becomes full will increase and so the cigarette maker will be stopped more frequently. Under such conditions, the cigarette packing machine hysteresis width could be reduced such that the packing machine can be run at full production speed for as much time as possible. A similar behaviour can be observed if the if the full production speed of the cigarette packing machine is greater than the full production speed of the cigarette maker. Therefore, the cigarette packing machine hysteresis width can be regarded as being inversely proportional to the efficiency of the cigarette maker. Thus, it can be considered that: packing machine hysteresis∞ (packing machine efficiency / maker efficiency) (8)

In view of these considerations, the inventors have found that a corrected value of the at least one operating parameter can advantageously be determined by multiplying a base line value of the at least one operating parameter by a factor substantially equal to the group comparative efficiency at the end of the first cycle time, or by the inverse thereof. Thus, a substantially linear relationship is established at all times between the at least one parameter and the ratio between the efficiency of the cigarette packing machine and the efficiency of the cigarette maker, or the inverse thereof.

Preferably, the base line value for the at least one parameter is determined as the value of the at least one parameter which, under conditions such that the efficiency of the cigarette maker is substantially equal to the efficiency of the cigarette packing machine, results in an optimised productivity of the group. This can be achieved, for instance, by simulation of the behaviour of the group, such that the impact on productivity of various values of the base line value for the at least one parameter can conveniently be assessed without needing to effectively operate the group.

During operation of the group, several further cycles may follow the first cycle. Preferably, the actual production output of the cigarette maker and the actual production output of the cigarette packing machine operating efficiency of the cigarette maker are monitored continuously during a further cycle time. Thus, it is advantageously possible to determine the current value of the efficiency of the cigarette maker or of the efficiency of the packing machine or both at any given time during any further cycle time. However, the production output of cigarette maker and of cigarette packing machine may alternatively be measured at predetermined intervals during any further cycle time. In some preferred embodiments, the method comprises operating the group for a further cycle time based on the updated at least one operating parameter; determining an operating efficiency of the cigarette maker over the further cycle time; determining an operating efficiency of the cigarette packing machine over the further cycle time; and determining a group comparative efficiency as the ratio between the operating efficiency of the cigarette maker and the operating efficiency of the cigarette packing machine at the end of the further cycle time. If the group comparative efficiency at the end of the further cycle time differs by at least 5 percent from the group comparative efficiency at the beginning of the further cycle time, the at least one operating parameter is reset at a further updated value depending on the group comparative efficiency at the end of the further cycle time. Otherwise, if the group comparative efficiency at the end of the further cycle time differs by less than 5 percent from the group comparative efficiency at the beginning of the further cycle time, the at least one operating parameter is maintained unchanged.

This is advantageous in that a check is carried out to ascertain whether, between the beginning and the end of the further cycle, the behaviour of the automated units in the group has changed significantly. This is assessed via the determination of any variation in the group comparative efficiency between the beginning and the end of the further cycle. If the behaviour of any one of the automated units in the group has remain substantially unchanged, there is no actual need to reset the at least one parameter. On the other hand, if a relevant change has occurred in the behaviour of any one of the automated units in the group, then it is preferable that the at least one parameter be reset at an updated value which accounts for the change.

Preferably, the step of resetting the at least one operating parameter comprises determining a further updated value of the at least one operating parameter based on the value of the ratio between the measured/determined operating efficiency of the cigarette maker and the measured/determined operating efficiency of the cigarette packing machine at the end of the further cycle time. If the updated value of the at least one parameter is in a range from a predetermined lower boundary value of the at least one parameter to a predetermined upper boundary value of the at least one parameter, the at least one operating parameter is reset at the determined updated value. Otherwise, if the updated value of the at least one parameter is less than the predetermined lower boundary value of the at least one parameter or greater than the predetermined upper boundary value of the at least one parameter, the at least one operating parameter is maintained unchanged.

As an alternative, the step of resetting the at least one operating parameter may comprise determining a further updated value of the at least one operating parameter based on the value of the comparative group efficiency at the end of the further cycle time. If the further updated value of the at least one parameter is in the range from a lower boundary value of the at least one parameter to an upper boundary value of the at least one parameter, the at least one operating parameter is reset at the further updated value. If the further updated value of the at least one parameter is less than the lower boundary value of the at least one parameter, the at least one operating parameter is reset at the lower boundary value of the at least one parameter. If the further updated value of the at least one parameter is greater than the upper boundary value of the at least one parameter, the at least one operating parameter is reset at the upper boundary value of the at least one parameter.

Thus, a check that the further updated value falls within an acceptable range is repeated at the end of each further cycle. This is advantageous in that it ensures stability of operation of the group during production.

In alternative embodiments, the method comprises operating the group for a predetermined further cycle time based on the adjusted at least one operating parameter; determining an operating efficiency of the cigarette maker over the further cycle time; determining an operating efficiency of the cigarette packing machine over the further cycle time; and determining a group comparative efficiency as the ratio between the operating efficiency of the cigarette maker and the operating efficiency of the cigarette packing machine at the end of the further cycle time.

If the operating efficiency of the cigarette maker at the end of the further cycle time is less than a base line maker efficiency, the average base line maker efficiency during the further cycle time is assumed as the current value of the operating efficiency of the cigarette maker. Otherwise, if the operating efficiency of the cigarette maker at the end of the further cycle time is at least as great as a base line maker efficiency, the operating efficiency of the cigarette maker at the end of the further cycle time is assumed as the current value of the operating efficiency of the cigarette maker.

If the operating efficiency of the cigarette packing machine at the end of the further cycle time is less than a base line packer efficiency, the average base line packer efficiency during the further cycle time is assumed as the current value of the operating efficiency of the cigarette packing machine. Otherwise, if the operating efficiency of the cigarette packing machine at the end of the second cycle is at least as great as a base line maker efficiency, the operating efficiency of the cigarette packing machine at the end of the second cycle is assumed as the current value of the operating efficiency of the cigarette packing machine.

In such alternative embodiments, the method further comprises determining a current comparative group efficiency as the ratio between the current value of the operating efficiency of the cigarette maker and the current value of the operating efficiency of the cigarette packing machine. Then, if the current comparative group efficiency differs by at least 5 percent from the comparative group efficiency from the comparative group efficiency at the beginning of the further cycle time, the at least one operating parameter is reset at a further updated value depending on the current comparative group efficiency. Otherwise, if the current comparative group efficiency differs by less than 5 percent from the comparative group efficiency from the comparative group efficiency at the beginning of the further cycle time, the at least one operating parameter is maintained unchanged.

By considering an average value of the efficiency of the automated units in the group, it is advantageously possible to dilute possible disturbances that may result from stops of the cigarette maker or the cigarette packing machine caused not by the buffer filling level reaching 100 percent or 0 percent, but by other reasons such as deliberate production interruptions.

Preferably, the step of resetting the at least one operating parameter comprises determining a further updated value of the at least one operating parameter based on the current comparative group efficiency.

In some embodiments, if the further updated value of the at least one parameter is in the range from a lower boundary value of the at least one parameter to an upper boundary value of the at least one parameter, the at least one operating parameter is reset at the further updated value. Otherwise, if the further updated value of the at least one parameter is less than the lower boundary value of the at least one parameter or greater than the upper boundary value of the at least one parameter, the at least one operating parameter is maintained unchanged.

In alternative embodiments, if the further updated value of the at least one parameter is in the range from a lower boundary value of the at least one parameter to an upper boundary value of the at least one parameter, the at least one operating parameter is reset at the further updated value. Otherwise, if the further updated value of the at least one parameter is less than the lower boundary value of the at least one parameter, the at least one operating parameter is reset at the lower boundary value of the at least one parameter. Finally, if the further updated value of the at least one parameter is greater than the upper boundary value of the at least one parameter, the at least one operating parameter is reset at the upper boundary value of the at least one parameter.

A system for implementing a method according to the present invention comprises a first group comprising a cigarette maker, a cigarette packing machine and a buffer, wherein, with respect to a conveying direction, the cigarette maker is upstream of the buffer and the cigarette packing machine is downstream of the buffer. Operation of the cigarette maker and of the cigarette packing machine depends on a filling level of the buffer. The system further comprises first sensor means for detecting a filling level of the buffer and for measuring the production output of the cigarette maker and the production output of the cigarette packing machine in the first group. In addition, the system comprises a control unit operatively connected with any one of the cigarette maker, cigarette packing machine, buffer or any combination thereof in the first group, and configured for managing operation of the first group in accordance with a method as set out above.

The control unit is essentially configured to implement a control logic in accordance with the methods described above. Thus, the control unit ensures not only that the operation state of the cigarette maker and the cigarette packer and the filling level of the buffer are correlated, but also that the nature and quality of such correlation be verified and changed over time so as to adapt to possible variations in the efficiency of the cigarette maker or the cigarette packing machine or both.

In some embodiments, one such system comprises a further group comprising a cigarette maker, a cigarette packing machine and a buffer, wherein, with respect to a conveying direction, the cigarette maker is upstream of the buffer and the cigarette packing machine is downstream of the buffer, such that operation of the cigarette maker and of the cigarette packing machine depends on a filling level of the buffer. Further, the system comprises second sensor means for detecting a filling level of the buffer and for measuring the production output of the cigarette maker and the production output of the cigarette packing machine in the second group. The control unit is further operatively connected with the any one of cigarette maker, cigarette packing machine, buffer or any combination thereof in the second group, and is configured for managing operation of the first group and of the further group in accordance with a method as set out above.

This is advantageous in that, in systems where two or more such groups of automated units are running in parallel, the same logic can be implemented on the various groups based on the observation of the behaviour of all the automated units in the system. Thus, the overall productivity of the system can advantageously be enhanced.

The invention will be further described, by way of example only, with reference to the drawings of the accompanying Figures, wherein:

Figure 1 illustrates a qualitative example of parameters defining how operation of a cigarette maker and a cigarette packing machine correlate with the filling level of a buffer interposed between the cigarette maker and the cigarette packing machine;

Figure 2 is a flow chart illustrating the steps of a method according to the present invention; Figure 3 is a flow chart illustrating the steps of a preferred embodiment of a method according to the present invention; and

Figure 4 is a flow chart illustrating the steps of a further preferred embodiment of a method according to the present invention.

Figure 1 shows a number of operating parameters of a group comprising a cigarette maker, a cigarette packing machine and a buffer. The parameters correlate an operation state of the cigarette maker and the cigarette packing machine with the filling level of the buffer. They include the cigarette maker starting limit, the cigarette maker reduced speed limit, the cigarette maker hysteresis width, the cigarette packing machine starting limit, the cigarette packing machine reduced speed limit, and the cigarette packing machine hysteresis width.

One such group comprising a PROTOS PM 100 (from Hauni Maschinenbau AG, Germany) as the cigarette maker, a F550 (from Focke GmbH, Germany) as the cigarette packing machine, and a CAPRICORN (from ITM, The Netherlands) as the buffer has been set up. The PROTOS PM 100 has a full production speed of 10,000 cigarettes/minute. The F550 has a full production speed of 500 packs/minute, wherein each pack contains 20 cigarettes (this also corresponds to 10,000 cigarettes processed every minute). The CAPRICORN has an active capacity of 125,000 cigarettes with an upstream and downstream rate of 10,000 cigarettes/minute.

Base line values for the operating parameters listed were determined based on the results of simulations run on the assumption that the operating efficiency of the cigarette maker is substantially equal to the operating efficiency of the cigarette packing machine. The base line values were selected as the values of the operating parameters resulting in an optimised group productivity. The following Table 1 lists the base line values determined from the simulations.

Table 1 - Base Line Values for operating parameters of the group Boundary values have been set for the operating parameters to ensure a stable operation of the group. The following Table 2 lists the boundary values.

Operating Parameter Upper boundary value Lower boundary value

[percent [percent buffer filling level] buffer filling level] cigarette maker starting limit 95 90 cigarette maker reduced speed limit 95 90 cigarette maker hysteresis width 8 5 cigarette packing machine starting limit 10 5 cigarette packing machine reduced 10 5 speed limit

cigarette packing machine hysteresis 8 5 width

Table 2 - Base Line Values for operating parameters of the group

Figure 2 is a flow chart illustrating a first embodiment of a method in accordance with the present invention.

The above operating parameters of the group are set at respective starting values and the group is operated for a first cycle time of one hour. During this time, operation of the group is monitored such as to determine the operating efficiency of the cigarette maker, the operating efficiency of the cigarette packing machine and the ratio thereof, which is taken as a group comparative efficiency.

After 1 hour, corrected values of the operating parameters are determined as a function of the group comparative efficiency. Thus, an updated value of the cigarette maker starting limit is calculated by multiplying the related base line value by the determined value of the group comparative efficiency (see equation 1 ). Similar calculations are made for the cigarette maker reduced speed limit, the cigarette packing machine starting limit, the cigarette packing machine reduced speed limit, and the cigarette packing machine hysteresis width (see equations 2, 4, 5 and 6). An updated value of the cigarette maker hysteresis width is calculated by multiplying the related base line value by the inverse of the determined value of the group comparative efficiency.

The operating parameters are reset at such updated values. The group is run for a further cycle time of 1 hour. At the end of the further cycle time, the comparative group efficiency is determined again. If the comparative group efficiency has varied by at least 5 percent between the beginning and the end of the further cycle time, new updated values for the operating parameters are calculated as set out above, and the operating parameters are reset at such updated values. Otherwise, if the comparative group efficiency has varied by less than 5 percent between the beginning and the end of the further cycle time, the operating parameters are left unchanged.

Compared with an identical group operated with no adaptive control, an increase in uptime of about 0.25 percent was found when operating the group according to a method as illustrated in Figure 2. Figure 3 illustrates a second embodiment of a method according to the present invention. It will only be described here insofar as it differs from the embodiment of Figure 2.

A method as illustrated by the flow-chart of Figure 3 differs from the embodiment described above in that a further check is provided immediately after the updated values of the operating parameters have been determined. In practice, the updated value of each one of the operating parameters is compared with the corresponding boundary values. If the updated value falls within the boundary values, then it is used for resetting the value of the operating parameter. Otherwise, if the updated value exceeds the upper boundary value, the upper boundary value is used for resetting the value of the operating parameter. If, finally, the updated value falls below the lower boundary value, the lower boundary value is used for resetting the value of the operating parameter.

Compared with an identical group operated with no adaptive control, an increase in uptime of from about 0.6 percent to about 0.8 percent was found when operating the group according to a method as illustrated in Figure 3.

Figure 4 illustrates a third embodiment of a method according to the present invention. It will only be described here insofar as it differs from the embodiment of Figure 3.

A method as illustrated by the flow-chart of Figure 4 differs from the embodiment described above in that a further check is provided immediately after the determination of the updated values for the operating parameters. In practice, the current value of cigarette maker efficiency and cigarette packing efficiency are compared with a base line efficiency value (for example, 30 percent). If the current value of cigarette maker efficiency and cigarette packing efficiency is at least equal to the related base line value, then the current value of the cigarette maker efficiency and cigarette packing efficiency is used for the following check on the efficiency variation during the further cycle time. Otherwise, if the current value of cigarette maker efficiency and cigarette packing efficiency is below the related base line value, then an average value of the efficiency during the second cycle time is used for the following check on the efficiency variation.

Compared with an identical group operated with no adaptive control, an increase in uptime of about 0.9 percent was found when operating the group according to a method as illustrated in Figure 4. This can lead to an increase in the production of more than 385,000 cigarettes over a production period of three days.