METHOD FOR OPERATING A GRIPPING DEVICE FOR SEPARATED LAUNDRY PIECES FROM A LAUNDRY PILE

Description

[0001] The present invention relates to a method for operating a gripping device for separating laundry items from a pile of laundry according to the preamble of claim 1.

[0002] Such a method is known from EP 771 746 A1.

[0003] When separating laundry items from a pile, it is important to ensure process reliability that the picking of multiple items at once is avoided as much as possible. Another important aspect is the cycle time required to complete a picking process. This is particularly true in industrial laundries, where commercially used laundry is consistently processed. This processing typically includes a washing cycle. For a laundry sorting process, it is important to separate the laundry items during the process so that each item can be assessed individually.

[0004] The known gripping device comprises a suction nozzle unit for sucking up a piece of laundry lying on the pile of laundry. The suction nozzle unit comprises a nozzle arrangement consisting of at least one nozzle. The suction nozzle unit comprises a device for generating negative pressure at the opening of the nozzle arrangement.

[0005] The gripping device has gripping elements which are closed in such a way that the gripping elements grip the item of laundry when closed.

[0006] In the subject matter of EP 771 746 A1, the suction nozzle unit is movable relative to the gripping elements in the gripping device such that the distance of the suction nozzle unit from the pile of laundry can be changed relative to the distance of the gripping elements from the pile of laundry: ➢ from a first position in which the distance of the suction nozzle unit from the pile of laundry is less than the distance of the gripping elements from the pile of laundry, ➢ to a second position in which the distance of the suction nozzle unit from the pile of laundry is greater than the distance of the gripping elements from the pile of laundry.

[0007] A gripping process is carried out by the following sequence of steps: ➢ First step: Starting from the first position in which the suction nozzle unit creates negative pressure and in which the gripping elements are open, ➢ Second step: Transition to the second position, ➢ Third step: Closing of the gripping elements.

[0008] The known gripping device is operated according to the known solution by lowering the suction nozzle unit onto the pile of laundry so that the suction nozzle unit touches the pile of laundry. In this position, negative pressure is generated, and the suction nozzle unit is moved away from the pile of laundry relative to the gripping elements.

[0009] Such a procedure is also described in US 3 092 263 A. There too, a suction nozzle unit is lowered onto a pile of laundry so that the suction nozzle unit touches this pile of laundry. It is described that a negative pressure is created so that the item of laundry is sucked in, which at that moment is resting against the opening of the suction nozzle unit and touching it. It is further described that when the suction nozzle unit is lifted, this item of laundry is lifted from the pile of laundry. When the item of laundry has been completely lifted from the pile of laundry and is therefore hanging freely, the item of laundry passes through a light barrier as it is lifted. Immediately after the item has been completely passed through the light barrier, a gripping device above this light barrier closes to hold the item of laundry mechanically. The aim of this is to ensure that the item of laundry - a towel - is held in a defined position at one corner by the gripping device.The position of the suction nozzle unit on the surface of the towel is randomly distributed during the suction processes because the laundry pile is unorganized. If the position of the suction nozzle unit is not centered relative to the surface of the towel, the towel will hang down from the suction nozzle unit in such a way that one corner hangs lower than the others. The light barrier is only released again once this (lowest-hanging) corner has passed the light barrier. By closing the gripping device at this moment, it is possible to ensure that the gripping device only grips the one corner that is currently hanging lowest. In cases where the towel does hang "symmetrically" downwards, it is possible to leave the gripping device closed and deactivate the vacuum. The towel will then fall back down onto the pile of laundry, allowing another gripping process to be performed.

[0010] The present invention is based on the object of proposing a method by which the separation of laundry items from a pile of laundry is improved.

[0011] To this end, the method according to claim 1 comprises the following steps: To operate a gripping device for separating laundry items from a pile of laundry, the gripping device comprises a suction nozzle unit for sucking in a laundry item lying on the pile of laundry. The suction nozzle unit comprises a nozzle arrangement consisting of at least one nozzle. The suction nozzle unit comprises a device for generating negative pressure at the opening of the suction nozzle unit. The gripping device comprises gripping elements that can be cooperatively closed such that the gripping elements grip a laundry item in the closed state.

[0012] According to the present invention, the opening of the suction nozzle unit is at a distance (X) from the pile of laundry that is greater than "0" when the suction of a laundry item begins. The gripping elements close when a laundry item has been sucked into the suction nozzle unit in such a way that the opening of the suction nozzle unit is covered by the laundry item. The laundry item is only partially lifted from the pile of laundry when the gripping elements close.

[0013] The distance X can, for example, be in the range of a few centimeters, for example between one centimeter and 20 centimeters, preferably between one centimeter and 10 centimeters, particularly preferably between one centimeter and five centimeters, particularly preferably between one centimeter and four centimeters.

[0014] It has been shown that maintaining the distance X between the suction nozzle unit opening and the pile of laundry in the first position, and thus also in the first step, improves process reliability. This reduces the frequency of inadvertently picking up multiple items of laundry.

[0015] This advantage can be explained by the fact that when the negative pressure and the suction flow of the suction nozzle unit act on the pile of laundry, only the item of laundry that is on top of the pile of laundry is lifted with greater certainty than if the suction nozzle unit directly touches the pile of laundry.

[0016] This can be explained as follows. First, air is sucked in. The topmost item of laundry is lifted until it reaches the nozzle. The item below is "in the pile." When a laundry item is lifted, the pressure above the item is lower than the pressure below it. Due to the negative pressure above the pile, this works for the topmost item. For the next item, this only works to a limited extent. The pressure above the item of laundry, in the pile that is not "on top," is only moderately reduced by the suction nozzle because this air also has to flow through the fabric of the topmost item.

[0017] Thus, positioning the suction nozzle above the pile of laundry at a certain distance X results in - largely - reliably only one item of laundry being lifted (compared to lifting several items of laundry when the suction nozzle is "placed" on top).

[0018] It is also advantageous that the laundry is already gripped by the gripping elements even before it has been completely lifted from the pile. If the laundry is partially buried under other laundry items in the pile, the vacuum generated by lifting the item solely by raising the suction nozzle unit may not be sufficient to detach the laundry from the pile. This is advantageous when the laundry has been gripped by the gripping elements and is lifted from the pile when the gripping elements are lifted.

[0019] Advantageously, the laundry item can initially be lifted a short distance after being vacuumed using only the suction nozzle unit. This ensures that any laundry that is accidentally vacuumed up (in addition to the item being lifted) falls back down before the gripping elements close. As explained, the gripping elements close before the laundry item is completely lifted from the pile.

[0020] The suction nozzle unit and the gripping elements are movable relative to each other such that the distance (X) of the suction nozzle unit from the laundry pile can be varied relative to the distance of the gripping elements from the laundry pile. This change can occur from a first position, in which the distance (X) of the opening of the suction nozzle unit from the laundry pile is less than the distance of the gripping elements from the laundry pile, to a second position, in which the distance of the opening of the suction nozzle unit from the laundry pile is greater than the distance of the gripping elements from the laundry pile. A gripping process is carried out by the following steps: ➢ First step: In the first position, negative pressure is generated in the suction nozzle unit and the gripping elements are open. ➢ Second step: After a piece of laundry has been sucked up, a transition to the second position takes place in which the suction nozzle unit in the gripping device is moved away from the pile of laundry relative to the gripping elements. ➢ Third step: The gripping elements are closed.

[0021] To achieve this objective, the method according to claim 2 comprises the following steps. For operating a gripping device for separating laundry items from a pile of laundry, the gripping device comprises a suction nozzle unit for sucking in a laundry item lying on the pile of laundry. The suction nozzle unit comprises a nozzle arrangement consisting of at least one nozzle. The suction nozzle unit comprises a device for generating negative pressure at the opening of the suction nozzle unit. The gripping device comprises gripping elements that can be cooperatively closed such that the gripping elements grip a laundry item in the closed state.

[0022] In the embodiment of the method according to claim 2, the gripping elements close with a rotation about a pivot point. The length of the gripping elements, starting from the pivot point of the rotational movement, is greater than the length of the suction nozzle unit, starting from the pivot point of the rotational movement of the gripping elements. The gripping elements are closed with a rotational movement after a piece of laundry has been sucked up by the suction nozzle unit.

[0023] In the embodiment according to claim 2, the gripping elements are so long that, when closed, they grip a piece of laundry sucked up by the suction nozzle unit "below" the opening of the suction nozzle unit. This advantageously simplifies the design of the gripping device compared to an embodiment according to claim 1 because the suction nozzle unit no longer needs to be movable relative to the gripping elements in the gripping device. In the embodiment according to claim 2, the gripping device is - if necessary - raised above the pile of laundry before the gripping elements are closed until the gripping elements close above the pile of laundry. The gripping elements only grip the piece of laundry that was sucked up by the suction nozzle unit and is therefore lifted from the pile of laundry when the gripping device is raised.

[0024] In the embodiment according to claim 3, an error handling routine is executed if, after generating the negative pressure and maintaining a distance X between the suction nozzle unit and the pile of laundry, it is detected that no laundry is being sucked in. During this error routine, the distance (X) is reduced and / or a stronger negative pressure is built up. This continues until the suction of a laundry item is detected.

[0025] This allows for advantageous adjustment of the process parameters, for example, if the laundry items in the pile are so intertwined that (initially) no item is lifted from the pile. Another reason could be that the pile contains (at least some) items whose fabric has a high specific gravity. A stronger vacuum is also required to (partially) lift such an item.

[0026] This stronger negative pressure can be achieved by creating a stronger negative pressure in the suction nozzle unit. Likewise, the distance (X) between the opening of the suction nozzle unit and the pile of laundry can be reduced.

[0027] Alternatively or additionally, a further error routine according to claim 4 can be designed such that, upon detection that no item of laundry is being sucked in, the gripping elements are closed such that these gripping elements grip the upper part of the laundry pile. The negative pressure can be switched off in this case. If necessary, the gripping elements must be lowered before closing so that they grip an upper part of the laundry pile when closing. After closing, the gripping elements are raised with the gripped upper part of the laundry pile. Subsequently, the gripping elements are opened in the raised position so that the raised upper part of the laundry pile falls back onto the laundry pile.

[0028] This can be used to loosen up the pile of laundry, so that when the laundry items are subsequently separated, items that were previously tangled up in the pile of laundry may be sucked up again.

[0029] If necessary, the gripping elements can perform a shaking movement in the raised position before opening to promote the release of the raised laundry items.

[0030] Claim 5 relates to an embodiment of the method in which, upon detection that several items of laundry have been gripped by the gripping elements after the suction nozzle unit has successfully picked up a single item of laundry, the following steps are performed. First, the gripping elements are raised to a position in which the gripped items of laundry are lifted from the pile of laundry. In In this raised position, the gripping elements are opened so that the grabbed laundry items fall back onto the pile of laundry.

[0031] This procedure can also advantageously be used to separate items of laundry that are entangled in one another, so that these items of laundry can be grasped individually in a subsequent grasping process.

[0032] In the embodiment according to claim 6, after the device for generating negative pressure is switched on, the device is operated at a first power level. After detecting the suction of a laundry item, the device is operated at a second power level, wherein the second power level is lower than the first power level.

[0033] This advantageously ensures that the first (higher) power level allows the laundry to be lifted. If it is detected that the laundry has been sucked in to such an extent that it covers the opening of the suction nozzle unit, the power level is advantageously lowered. It has been shown that this lower power level is sufficient during operation of the device to hold the laundry in the position in which it covers the opening of the suction nozzle unit.

[0034] By lowering the power level, it is advantageously prevented that an item of laundry that is located below the topmost item of laundry that is to be picked up individually is also sucked in.

[0035] If another item of laundry has already been sucked in by mistake, reducing the power level of the device for generating negative pressure can advantageously ensure that this item of laundry falls off again.

[0036] If the device for generating the vacuum comprises an electric motor, the electrical power consumed by the electric motor is determined by the electrical voltage applied to the terminals of the electric motor and the mechanical load opposing the movement of the electric motor. In this case, the reduction in power level is achieved by reducing the electrical voltage applied to the terminals of the electric motor.

[0037] According to the embodiment according to claim 7, the suction of a laundry item is detected by evaluating one or more of the following measured variables: ➢ Change in the speed of the drive unit of the device for generating negative pressure, ➢ Power consumption of the drive unit of the device for generating negative pressure, ➢ Change in the air flow rate when the device is switched on, ➢ Change in the pressure inside the nozzle unit, > optical evaluation.

[0038] Analyzing the change in speed of the vacuum cleaner's drive unit is useful because when a laundry item is sucked in to such an extent that the opening of the suction nozzle unit is covered, the air flow is reduced. This leads to a drop in the vacuum cleaner's speed. This drop in speed can be analyzed.

[0039] If the opening of the suction nozzle unit is covered by a piece of laundry, the power consumption of the vacuum generation device increases. If such a sudden increase in power consumption is detected, it can also be deduced that a piece of laundry has been sucked in.

[0040] Both of these effects occur when the device for generating negative pressure uses an electric motor. If the air flow rate decreases because the airflow encounters greater flow resistance, the speed of the electric motor decreases. This results in higher power consumption of the electric motor if a constant voltage is applied to its terminals.

[0041] It is also possible to evaluate a change in the air flow rate when the device is switched on. This change in the air flow rate occurs directly related to a piece of laundry covering the opening of the suction nozzle.

[0042] It is also possible to evaluate the change in pressure inside the suction nozzle unit. This can also be used to detect whether the opening of the suction nozzle unit is covered by a piece of laundry.

[0043] The evaluation of all of these measured variables shows that when the device for generating negative pressure is switched on and the opening of the suction nozzle unit is located above the pile of laundry, the control of the power level of the device for generating negative pressure functions better within the meaning of claim 3. The sudden change in the respective measured variable is then due to the fact that immediately after the device for generating negative pressure is switched on, the opening of the suction nozzle unit is still free and a corresponding amount of air flows through the opening of the suction nozzle unit. If the item of laundry is sucked in and covers the opening of the suction nozzle unit, this leads to a sudden change in the respective measured variable. This sudden change can be detected with a high degree of reliability and even with a short time delay.

[0044] It is also possible to provide an optical evaluation. This optical evaluation can consist of a light barrier located below the suction nozzle unit or inside the suction nozzle unit near the opening of the suction nozzle unit. The optical evaluation can also consist of a camera scanning the entire area, so that an image analysis can determine whether a piece of laundry is covering the opening of the suction nozzle unit.

[0045] In the embodiment according to claim 8, the power level at which the device for generating negative pressure in the suction nozzle unit is operated depends on a detection of the type of fabric of the laundry items in the pile of laundry.

[0046] If the fabric has a high specific gravity, the power level can be set higher than for a fabric with a lower specific gravity.

[0047] The fabric type can be identified by affixing an RFID chip to the laundry items in the pile. By analyzing the RFID chips, it is then possible to determine—among other data—whether the fabric has a higher or lower specific gravity.

[0048] It can also be determined whether the fabric is rather dense or whether the fabric has pores through which air can flow.

[0049] It is also possible to identify the type of fabric by evaluating the pile of laundry with a camera array.

[0050] In the embodiment according to claim 9, the device for generating negative pressure is switched off when the gripping elements are closed.

[0051] This proves to be useful because the individual laundry item is then held separately by the gripping elements. This item can then be lifted further away from the pile of laundry. The generation of negative pressure by the suction nozzle unit is no longer required in this situation.

[0052] In the embodiment of the method according to claim 10, the shape and position of the laundry pile are detected. From the shape and position of the laundry pile, a target position for the opening of the suction nozzle unit is determined such that, upon reaching this target position, the opening of the suction nozzle unit is at a distance (X) from the laundry pile. The gripping device is moved to this target position to execute the first step.

[0053] It has proven advantageous to position the gripping device for carrying out the process above the highest point of the laundry pile. With the item of laundry then on top, the likelihood of this item being partially buried beneath other items in the pile is lower than with other items in the pile. This facilitates suction and also facilitates subsequent lifting of the item from the pile during the separation process.

[0054] By recording the shape and position of the laundry pile, a target position can also be defined that is located at a distance X above the highest point of the laundry pile.

[0055] Identifying such a target position for the opening of the suction nozzle unit has significant advantages for increasing the cycle frequency. Once an item of laundry has been gripped and separated, it is lifted from the pile of laundry by moving the gripping device away from the pile of laundry. Once this item of laundry has been put down, the gripping device must be repositioned relative to the pile of laundry in order to be able to separate and grip the next item of laundry. Because the position of the opening of the suction nozzle should be at a distance X from the pile of laundry, this positioning cannot simply be achieved by moving the gripping device towards the pile of laundry until it hits the pile of laundry. Once the target position has been determined, a trajectory for an optimal movement sequence to reach the target position can be determined based on the current position of the opening of the suction nozzle unit.Likewise, a speed profile along this trajectory can be defined in such a way that the gripping device is moved along the trajectory at the highest possible speed and at the same time is braked in good time before reaching the target point, so that the opening of the suction nozzle unit is braked just when the target position is reached and comes to a standstill.

[0056] An embodiment of the invention is illustrated in the drawing. The figure shows: Fig. 1 to 4::Representations of a gripping device with a suction nozzle unit and gripping elements above a pile of laundry in different positions and operating states and Fig. 5: a block diagram to illustrate the sequence of the method according to the present invention.

[0057] The Figures 1 to 4show representations of a gripping device 1 with a suction nozzle unit 2 and gripping elements 3, 4 above a pile of laundry 5 in different positions and operating states

[0058] Figure 1 shows the gripping device 1, in which this gripping device 1 is located above the pile of laundry 5. It can be seen that the opening 6 of the suction nozzle unit 2 has a distance X from the pile of laundry 5 that is greater than "0".

[0059] In the presentation of the Figure 1 It can be seen that air flows in through the opening 6 of the suction nozzle unit 2, which air is sucked in from the side of the suction nozzle unit 2 and flows between the opening 6 of the suction nozzle unit 2 and the pile of laundry 5.

[0060] It can be seen that gripping elements 3 and 4 are open.

[0061] The device for generating the negative pressure in the suction nozzle unit 2 is shown in the illustration of Figure 1in operation. This sucks in the air and flows between the pile of laundry 5 and the opening 6 of the suction nozzle unit 2 into the opening 6 of the suction nozzle unit 2. This creates a negative pressure.

[0062] In this first position, the opening 6 of the suction nozzle unit 2 is closer to the pile of laundry 5 than the gripping elements 3 and 4. In the illustrated embodiment, this is already due to the fact that the two gripping elements 3 and 4 are open and protrude laterally in an upper position - above the opening 6 of the suction nozzle unit 2.

[0063] Figure 2 shows the situation as in Figure 1 with the difference that due to the negative pressure, the topmost item of laundry in the pile of laundry 5 was sucked in to such an extent that this item of laundry covered the opening 6 of the suction nozzle unit 2.

[0064] The Figures 1 to 4The gripping device 1 shown relates to an embodiment in which the suction nozzle unit 2 in the gripping device 1 is movable in the vertical direction relative to the gripping elements 3 and 4. This is shown in the Figure 3 symbolized by the arrow 301.

[0065] By lifting the suction nozzle unit 2 in the gripping device 1, the sucked-in laundry item is lifted further away from the pile of laundry.

[0066] The two arrows 302 and 303 refer to the rotational movement of the two gripping elements 3 and 4 during closing. It can be seen that the two gripping elements 3 and 4 close above the pile of laundry 5. In this case, it again proves advantageous for the suction nozzle unit 2 to be moved upward relative to the gripping elements 3 and 4, so that the suctioned laundry item is located between the gripping elements 3 and 4 before they are closed.

[0067] In addition, the relative movement of the suction nozzle unit 2 relative to the gripping elements 3 and 4 in the gripping device 1 ensures that the gripping elements 3 and 4 close below the opening 6 of the suction nozzle unit 2.

[0068] Figure 4 shows the gripping device 1 in the position in which the suction nozzle unit 2 in the gripping device 1 has been moved upward relative to the gripping elements 3 and 4, and in which the gripping elements 3 and 4 are closed, thus gripping the laundry item. It can be seen that the device for generating the negative pressure is switched off. The laundry item is held solely by the closed gripping elements 3 and 4.

[0069] Based on the Figures 3 and 4It can be explained that for the implementation of the present invention, it is not absolutely necessary that the suction nozzle unit 2 in the gripping device 1 is movable upwards relative to the gripping elements 3 and 4 (ie: the movement according to the arrow 301 is not absolutely necessary). The assignment of the position of the suction nozzle unit 2 to the pivot point 401 of the gripping elements 3 and 4 can also be carried out statically, as shown in Figure 4 The gripping elements 3 and 4 thus close below the opening 6 of the suction nozzle unit 2. If the two gripping elements 3 and 4 are turned as far as shown in the Figures 1 and 2 As shown, the two gripping elements 3 and 4 are located above the opening 6 of the suction nozzle unit 2 even when the suction nozzle unit 2 is positioned (statically) as high as possible within the gripping device 1, as shown in Figure 4was shown. With such a configuration, it is then also possible to position the opening 6 of the suction nozzle unit 2 above the pile of laundry 5 at a distance X, so that the gripping elements 3 and 4 are nevertheless located further away from the pile of laundry 5 than the opening 6 of the suction nozzle unit 2. This configuration corresponds to the second alternative for implementing the second step mentioned in claim 1.

[0070] Figure 5 shows a block diagram illustrating the sequence of the method according to the present invention.

[0071] In function block 501, a process cycle begins. The suction nozzle unit is positioned a specific distance X from the top of the laundry pile. The device for generating negative pressure is activated.

[0072] Function block 502 checks whether, after a certain time has elapsed, a piece of laundry has been sucked in, so that this piece of laundry covers the opening of the suction nozzle unit. This check can be performed by evaluating one of the measured variables mentioned in connection with claim 3.

[0073] If it has been detected that no item of laundry has been sucked in even after a certain time has elapsed, the suction nozzle unit can be positioned closer to the pile of laundry (reducing the distance X) and / or the power of the device for generating the negative pressure can be increased, as shown in function block 503.

[0074] If a piece of laundry has been sucked in, the power of the device for generating negative pressure can be reduced according to function block 504.

[0075] The suction nozzle unit is retracted relative to the gripping elements according to functional block 505. If the gripping elements are sufficiently long relative to the length of the suction nozzle unit according to the description of claim 1 in the second alternative of the second step, the gripping device can also be lifted entirely from the pile of laundry, so that the gripping elements close above the pile of laundry in the subsequent step of functional block 506.

[0076] According to function block 506, the gripping elements are closed and the drive unit for generating negative pressure is switched off.

Claims

1. Method for operating a gripping device (1) for separating laundry items from a laundry pile (5), ➢ wherein the gripping device (1) has a suction nozzle unit (2) for sucking up a laundry item lying on the laundry pile (5), ➢ wherein the suction nozzle unit (2) has a nozzle assembly, which consists of at least one nozzle, ➢ wherein the suction nozzle unit (2) has a device for generating a vacuum at the opening (6) of the suction nozzle unit (2), ➢ wherein the gripping device (1) has gripping elements (3, 4), which are closed in cooperation in such a way that the gripping elements (3, 4) grip the laundry item in the closed state, characterised in that ➢ the opening (6) of the suction nozzle unit (2) has (201) a distance (X) from the laundry pile (5) that is greater than "0" when suction of a laundry item begins, ➢ the gripping elements (3, 4) close when a laundry item has been sucked up by the suction nozzle unit (2) in such a way that the opening (6) of the suction nozzle unit (2) is covered by the laundry item, and ➢ the laundry item is only partially lifted from the laundry pile (5) when the gripping elements (3, 4) close, ➢ the suction nozzle unit (2) and the gripping elements (3, 4) can be moved relative to one another such that the distance (X) from the suction nozzle unit (2) to the laundry pile (5) can be changed relative to the distance from the gripping elements (3, 4) to the laundry pile (5): ➢ from a first position, in which the distance (X) from the opening (6) of the suction nozzle unit (2) to the laundry pile (5) is less than the distance from the gripping elements (3, 4) to the laundry pile (5), ➢ to a second position, in which the distance from the opening (6) of the suction nozzle unit (2) to the laundry pile (5) is greater than the distance from the gripping elements (3, 4) to the laundry pile, ➢ wherein a gripping process is performed with the following steps: ➢ First step: In the first position, a vacuum is generated in the suction nozzle unit (2) and the gripping elements (3, 4) are open, ➢ Second step: After sucking up a laundry item, a transition into the second position occurs, in which second position the suction nozzle unit (2) in the gripping device (1) is moved away from the laundry pile (5) relative to the gripping elements (3, 4), ➢ Third step: The gripping elements (3, 4) are closed.

2. Method for operating a gripping device (1) for separating laundry items from a laundry pile (5), ➢ wherein the gripping device (1) has a suction nozzle unit (2) for sucking up a laundry item lying on the laundry pile (5), ➢ wherein the suction nozzle unit (2) has a nozzle assembly, which consists of at least one nozzle, ➢ wherein the suction nozzle unit (2) has a device for generating a vacuum at the opening (6) of the suction nozzle unit (2), ➢ wherein the gripping device (1) has gripping elements (3, 4), which are closed in cooperation in such a way that the gripping elements (3, 4) grip the laundry item in the closed state, characterised in that ➢ the opening (6) of the suction nozzle unit (2) has (201) a distance (X) from the laundry pile (5) that is greater than "0" when suction of a laundry item begins, ➢ the gripping elements (3, 4) close when a laundry item has been sucked up by the suction nozzle unit (2) in such a way that the opening (6) of the suction nozzle unit (2) is covered by the laundry item, and the laundry item is only partially lifted from the laundry pile (5) when the gripping elements (3, 4) close, ➢ the gripping elements (3, 4) close with a rotation about a rotation point (401), ➢ the length of the gripping elements (3, 4) starting from the centre of rotation (401) of the rotary movement is greater than the length of the suction nozzle unit (2) starting from the centre of rotation (401) of the rotary movement of the gripping elements (3, 4), and ➢ the gripping elements (3, 4) are closed with a rotary movement (401) after a laundry item has been sucked up by the suction nozzle unit (2).

3. Method according to claim 1 or 2, characterised in that when a vacuum is generated in the suction nozzle unit without recognising the sucking up of a laundry item ➢ the distance (X) is reduced and / or ➢ a stronger vacuum is built up until the sucking up of a laundry item has been recognised.

4. Method according to any one of claims 1 to 3, characterised in that on recognising that no laundry items have been sucked up, ➢ the gripping elements (3, 4) are closed such that said gripping elements (3, 4) grip the top part of the laundry pile (5), ➢ the gripping elements (3, 4) are then lifted after gripping the top part of the laundry pile (5), ➢ the gripping elements (3, 4) are then opened in the lifted position, such that the lifted top part of the laundry pile (5) falls back onto the laundry pile.

5. Method according to any one of claims 1 to 4, characterised in that on recognising that several laundry items are gripped by the gripping elements after one laundry item has been sucked up by the suction nozzle unit (2), ➢ the gripping elements (3, 4) are lifted into a position in which the gripped laundry items are lifted from the laundry pile, and ➢ the gripping elements (3, 4) are opened in this lifted position such that the gripped laundry items fall back onto the laundry pile (5).

6. Method according to any one of claims 1 to 5, characterised in that ➢ after switching on the device to generate a vacuum, the device is operated at a first power level (201), ➢ after recognising that a laundry item has been sucked up, the device is operated at a second power level (204), ➢ wherein the second power level is lower than the first power level.

7. Method according to any one of claims 1 to 6, characterised in that a laundry item being sucked up is recognised (202) by evaluating one or more of the following variables: ➢ Speed change of the drive unit of the device for generating a vacuum, ➢ Power consumption of the drive unit of the device for generating a vacuum, ➢ Change in the air flow rate when the device is switched on, ➢ Change in pressure inside the suction nozzle unit (2), ➢ Visual evaluation.

8. Method according to any one of claims 1 to 7, characterised in that the power level at which the device for generating a vacuum in the suction nozzle unit (2) is operated is dependent on recognising the type of fabric of the laundry item in the laundry pile (5).

9. Method according to any one of claims 1 to 8, characterised in that the device for generating a vacuum is switched off if the gripping elements (3, 4) are closed (206).

10. Method according to any one of claims 1 to 9, characterised in that ➢ the shape and position of the laundry pile (5) is detected, ➢ a desired position for the opening (6) of the suction nozzle unit (2) is determined from the shape and position of the laundry pile (5) in such a way that the opening (6) of the suction nozzle unit (2) is at a distance (X) from the laundry pile (5) when this desired position is reached, ➢ the gripping device (1) is moved to this target position to perform the first step.