EP3509466A1

EP3509466A1 - Robotic window-cleaning system and safety cord system therefor

Info

Publication number: EP3509466A1
Application number: EP17757544.6A
Authority: EP
Inventors: Shai Abramson; Asaf Levin; Shalom Levin
Original assignee: Alfred Kaercher SE and Co KG
Current assignee: Alfred Kaercher SE and Co KG
Priority date: 2016-09-08
Filing date: 2017-08-25
Publication date: 2019-07-17
Anticipated expiration: 2037-08-25
Also published as: WO2018046316A1; GB2553562A; EP3509466B1; GB201615299D0

Abstract

The invention relates to a safety cord system for a window cleaning robot. The system comprises an anchor component, the anchor component being coupleable to, or adjacent to, a window; a cord; and a cord-handling unit, which is configured to be coupled to one of the anchor component and the robot and which comprises: a spool, which is configured to automatically rotate about a winding axis in a winding direction, the cord thereby being wound around the spool, the cord extending from a first end to a second end, the first end being secured at said spool, the second end being configured to be secured to the other of the anchor and the robot; and a braking mechanism, which is configured to halt the unwinding of the cord from the spool, thereby halting the robot's fall from the window, and which is activated when the angular velocity of the spool exceeds a threshold.

Description

TECHICAL FIELD

The present invention relates generally to robotic systems and, in particular, to robotic window-cleaning systems and safety cord systems therefor.

BACKGROUND

The use of automated devices is widespread nowadays, and finds countless applications. For instance, robots perform very precise and delicate tasks in the construction of electronic devices, or in medicine and aviation. Robots are also used in applications which require motion, notably, for automatic warehouses, where goods are retrieved and stored by means of computer-actuated robots. Other applications include, e.g., fetching raw materials in the course of industrial manufacturing, and removing and packaging finished pieces.

Attempts have also been made to exploit robots for tasks around the home or garden, such as lawn mowing, snow-blowing, leaf-clearing, floor cleaning, pool cleaning and vacuum cleaning.

By their very nature, autonomous machines such as robots represent a significant labour- saving for consumers. Repetitive and time-consuming tasks may now be carried out without significant supervision or instruction by the user of such autonomous machines.

Window cleaning is an example of such a repetitive and time-consuming task. A robotic window cleaner may be valuable not only in reducing manual labour, but also in allowing the cleaning of window surfaces that are usually hard to access, such as the external surfaces of windows and/or windows that are high above the ground.

A few window cleaning robots are currently available to the consumer, such as the WinBot and Hobot. However, in many respects, robotic window cleaners have not yet been perfected.

Typically, window-cleaning robots will include some kind of system that enables them to attach themselves to the window so that they may clean the window. However, such attachment systems may occasionally fail, resulting in the robot falling off the window. This may lead to the robot to becoming damaged, owing to the impact with the ground; more seriously, the falling robot may present a risk to the safety of the user or, more generally, people in the vicinity of the window, especially where a robot has been attached to to the exterior surface of a window and even more so where that window is a number of stories above the ground.

SUMMARY

Aspects of the invention are set out in the appended claims.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS

In one aspect of the present invention, a safety cord system for a window cleaning robot comprises:

an anchor component, the anchor component being coupleable to, or adjacent to, a window;

a cord; and a cord-handling unit, which is configured to be coupled to one of the anchor component and the robot and which comprises:

a spool, which is configured to automatically rotate about a winding axis in a winding direction, the cord thereby being wound around the spool, the cord extending from a first end to a second end, the first end being secured at said spool, the second end being configured to be secured to the other of the anchor and the robot; and a braking mechanism, which is configured to halt the unwinding of the cord from the spool, thereby halting the robot's fall from the window, and which is activated when the angular velocity of the spool exceeds a threshold.

In a preferred embodiment, the spool is mechanically biased so as to wind the cord around the winding axis.

In a preferred embodiment, a cord guiding feature, in which the cord is slidably received, is provided within the cord handling unit. Preferably, the cord guiding feature is configured as an aperture in the cord-handling unit, more preferably the aperture is provided in the exterior surface of the cord handling unit.

In a preferred embodiment, the cord handling unit is configured to be rotatably coupled to said one of the anchor component and the robot, such that it rotates about an axis perpendicular to the window surface.

In a preferred embodiment, said axis perpendicular to the window surface is the winding axis.

In a preferred embodiment, the braking mechanism comprises at least one moveable element, each of which is moveably mounted on the spool, whereby rotation of the spool about the winding axis causes the moveable element in question to move radially outwards relative to the winding axis; and when the radial distance of any of the moveable elements is equal to or greater than a threshold radial distance, a force is applied to the moveable element(s) in question, the force opposing rotation of the spool in the unwinding direction.

In a preferred embodiment, said forces opposing rotation of the spool in the unwinding direction result in a generally constant tension being applied to the cord until the robot's fall from the window is halted.

In a preferred embodiment, each moveable element is pivotably mounted on the spool.

In a preferred embodiment, each moveable element is mechanically biased towards the winding axis.

In a preferred embodiment, when the radial distance of any of the moveable elements is equal to or greater than a threshold radial distance, the moveable element(s) in question contact(s) one or more other components of the braking mechanism, said one or more other components applying said force to the moveable element(s) in question.

In a preferred embodiment, the force applied to the moveable element results from friction between one or more components co-rotating with the spool and one or more components not co-rotating with the spool. In a preferred embodiment, the breaking mechanism further comprises a rotatable brake component, which is configured such that it can rotate about the winding axis; when the radial distance of any of the moveable elements is equal to or greater than the threshold radial distance, the moveable element(s) in question engage(s) with the rotatable brake component, thereby causing the rotatable brake component to co-rotate with the spool, the rotatable brake component being configured such that it experiences a frictional force opposing such rotation.

In a preferred embodiment, the rotatable brake component comprises a plurality of retaining features that are circumferentially arranged about said winding axis, the retaining features being arranged such that, when the radial distance of any of the moveable elements is equal to or greater than the threshold radial distance, the moveable element(s) in question engage(s) with one of the retaining features.

In a preferred embodiment, once a moveable element is engaged with a retaining feature, the retaining feature in question inhibits radial movement of the moveable element in question.

In a preferred embodiment, each retaining feature includes a surface for engaging with a corresponding surface on one of the moveable elements, the retaining feature surface extending in the unwinding direction with increasing radial distance from the winding axis.

In a preferred embodiment, the moveable elements and retaining features have

complementary shapes.

In a preferred embodiment, the breaking mechanism further comprises an opposing brake component, the rotatable brake component and the opposing brake component being arranged in contact with each other such that rotation of rotatable brake component relative to the opposing brake component generates frictional force opposing such rotation.

In a preferred embodiment, the rotatable brake component and the opposing brake component each include at least one frictional surface, the frictional surface(s) of the rotatable brake component being in contact with the frictional surface(s) of the opposing brake component so as to provide the frictional force opposing relative rotation of the components; the rotatable brake component and the opposing brake component are biased towards one another so that their respective frictional surfaces are pressed together.

In a preferred embodiment, the rotatable brake component and the opposing brake component each include a plurality of said frictional surfaces, the frictional surfaces being arranged parallel to one another, preferably each frictional surface is substantially normal to the winding axis.

In a preferred embodiment, the cord guiding feature is provided within the opposing brake component, preferably the cord guiding feature is provided in an outer portion of the opposing brake component.

In a preferred embodiment, the opposing brake component is configured such that it can rotate about the winding axis.

In a preferred embodiment, the cord-handling unit further comprises a housing; when the radial distance of any of the moveable elements is equal to or greater than a threshold radial distance, the moveable element(s) in question contact(s) the housing, the housing substantially preventing relative rotation of the spool thereafter.

In a preferred embodiment, the cord is elastic, its length extending elastically in the process of halting the robot's fall from the window.

In a preferred embodiment, the second end of the cord is connected to an elastically extensible element, which is configured to be secured to said other of the anchor and the robot, thereby securing the cord to said other of the anchor and the robot, the length of said elastic element extending elastically in the process of halting the robot's fall from the window; preferably said elastic element comprises a spring.

In a preferred embodiment, the cord guiding feature is provided within the housing.

In a preferred embodiment, the housing is configured such that it can rotate about the winding axis.

In a preferred embodiment, the anchor component comprises a suction cup.

In a preferred embodiment, the cord-handling unit is coupled to the anchor component and further comprises a second anchor component, the second anchor component being coupleable to, or adjacent to, the window, the second end of the cord being secured at said second anchor component; the robot is slidably coupleable to the cord.

In a preferred embodiment, the safety cord system further comprises a second cord, extending from a first end to a second end, the first end being slidably coupled to the first cord, the second end being securely coupleable to the robot, the robot thereby being slidably coupled to the first cord.

In a preferred embodiment, the second anchor component comprises a suction cup.

In a further aspect of the present invention, a robotic window-cleaning system comprises a window-cleaning robot coupled to the safety cord system of the aforementioned type.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawings, in which:

Figure 1 is a view from behind of a window-cleaning robot attached to a window by an inbuilt attachment system, as well as by a safety cord system;

Figure 2 is an exploded view of an example of an anchor component and the constituent parts of an example of a cord-handling unit, which are suitable for use in the safety cord system of Figure 1 ;

Figure 3 is a perspective view of the cord-handling unit and anchor component of Figure 2;

Figure 4 is a perspective view of the anchor component and the cord-handling unit Figure 2, with an outer portion of an opposing brake component removed so as to better illustrate other constituent parts of the cord-handling unit;

Figure 5 is a perspective view from below of the spool of the cord-handling unit of Figure 2; Figure 6 is a perspective view from above of the rotatable brake component and the opposing brake component of the cord-handling unit of Figure 2, again with the outer portion of the opposing brake component removed;

Figure 7 is a perspective view from above of the anchor component, and the rotatable brake component and the opposing brake component of the cord-handling unit of Figure 2, again with the outer portion of the opposing brake component removed;

Figure 8 is a perspective view of a cross-section taken through the cord-handling unit of Figure 2, again with the outer portion of the opposing brake component removed;

Figure 9 is a is a perspective view from above of the anchor component, and the brake pads of the rotatable brake component and the opposing brake component of the cord-handling unit of Figure 2, with various of the constituent parts of cord-handling unit removed for clarity;

Figure 10 is a is a perspective view from below of the brake pads of the rotatable brake component and the opposing brake component of the cord-handling unit of Figure 2, as well as a spring that biases the brake pads towards each other;

Figure 1 1 is a perspective view from above of the anchor component of the cord-handling unit of Figure 2;

Figure 12 is a view from behind of a window-cleaning robot attached to a window by an inbuilt attachment system, as well as by a safety cord system of similar design to that of Figure 1 but with two anchor components; and

Figure 13 is a schematic diagram of an example of a window-cleaning robot 1 that may be utilised with the safety cord systems of Figures 1 to 12.

DETAILED DESCRIPTION OF THE DRAWINGS

Turning first to Figure 1 , there is shown a view from behind of a window-cleaning robot 1 attached to a window 1000 by an in-built attachment system, as well as by a safety cord system 5 according to an example embodiment.

The robot's attachment system 600 (illustrated schematically in Figure 13) enables the robot 1 to attach itself to the window surface and keeps it attached thereto. The attachment system 600 may, for example, utilise suction forces to attach the robot to the window surface. Accordingly, it may, for instance, include one or more vacuum pumps to provide a suction force and one or more sealing members that contact the window surface so as to seal a space between the robot and the window surface, with the vacuum pump(s) being configured to reduce the air pressure in this space.

The attachment system 600 might instead (or in addition) utilise magnetic forces to attach the robot 1 to the window surface. Accordingly, the user may be provided with a paired device that is placed on the opposite surface of the window to the side on which the robot 1 operates, with the robot 1 and the paired device being magnetically attracted to each other. Hence, the robot 1 and/or the paired device may, for instance, include one or more magnetic members, such as electromagnets or permanent magnets. The safety-cord system may act as a back-up attachment system, in case the in-built attachment system 600 of the robot fails (regardless of the particular type of in-built attachment system 600).

Returning now to Figure 1 , as may be seen, the safety cord system includes an anchor component 20, a cord 30 and a cord-handling unit 10. As is apparent from the drawing, the anchor component 20 is coupled to the surface of the window 1000, thereby attaching the safety-cord system thereto.

In the particular embodiment shown in Figure 1 , the cord-handling unit 10 is coupled to the anchor component 20. More particularly, the cord handling unit 10 is configured to be rotatably coupled to the anchor component 20, such that it rotates about an axis

perpendicular to the surface of the window 1000. The cord 30 extends from a first end, which is secured to a spool 40 within the cord-handling unit 10, to a second end, which is secured to the robot 1 .

The spool 40 (not visible in Figure 1 ) is configured to automatically rotate about a winding axis in a winding direction, with the cord 30 thereby being wound around the spool 40. This may reduce the risk of the robot becoming entangled in loose cord, which might reduce the efficiency of the robot or even cause the robot to fall off the window 1000.

In particular examples, the tension applied to the cord by the winding mechanism may be substantially less than the driving force that the robot's movement system generates when moving around the window. A possible consequence of this is that the robot's efficiency is not substantially impacted by the winding of the cord around the spool 40.

The cord-handling unit 10 further includes a braking mechanism, particular examples of which will be described below with reference to Figures 2-1 1 . The braking mechanism is configured to halt the unwinding of the cord from the spool 40, thereby halting the robot's fall from the window. As the spool 40 is configured to automatically rotate about the winding axis, thereby winding the cord around itself, the distance that the robot may fall before being caught by the braking system may be fairly limited. This may reduce the risk of the robot hitting the floor or ground, potentially damaging itself.

In particular examples, the spool 40 may be configured to automatically wind the cord around itself so as to remove substantially all slack from the cord. In certain of these particular examples, the winding mechanism may apply little or no tension to the cord; for instance, as discussed above, the tension applied to the cord by the winding mechanism may be substantially less than the driving force that the robot's movement system generates when moving around the window.

Further, the braking mechanism is activated when the angular velocity of the spool 40 exceeds a threshold. This may be contrasted with approaches where the braking mechanism is constantly active, which may reduce the efficiency with which the robot operates on the window surface, for instance necessitating more frequent recharging in cases where the robot operates with a rechargeable internal power source.

This threshold may, for example, be chosen so as to be substantially more than the maximum velocity with which the robot may move around the window surface. A possible consequence is that the braking mechanism is not inadvertently triggered by movement of the robot around the window.

While in the particular example embodiment of Figure 1 , the cord-handling unit 10 is coupled to the anchor component 20, this is by no means essential and in other examples the cord- handling unit 10 may instead be coupled to the robot 1 , with the first end of the cord 30 again being secured to the spool 40 within the cord-handling unit 10, but with the second end of the cord 30 being secured instead to the anchor component 20. In such cases, the cord handling unit may be configured to be rotatably coupled to the robot, such that it rotates about an axis perpendicular to the window surface.

Attention is now directed to Figure 2, which is an exploded view of an example of an anchor component 20 and the constituent parts of an example of a cord-handling unit, which are suitable for use in the safety cord system of Figure 1. The drawing clearly shows the spool 40 of the cord-handling unit and indicates the winding axis A-A about which the spool 40 is configured to rotate. Figure 2 also shows the anchor component 20 to which the cord- handling unit is coupled.

In the particular example shown in Figure 2, the spool 40 is mechanically biased so as to wind the cord 30 around the winding axis A-A. For instance, the spool 40 may be biased by a pre-loaded spring within the cord-handling unit.

As an alternative to mechanical biasing (or perhaps in addition to mechanical biasing), the cord-handling unit may include an electrically-powered winding mechanism. For example, this might include an electrical motor and/or a system of electromagnets.

As may also be seen from Figure 2, the example of a cord-handling unit includes, in addition to the spool 40, a rotatable brake component 50, and an opposing brake component 60. The rotatable brake component 50 and the opposing brake component 60 form part of the braking mechanism for the cord-handling unit shown in Figure 2.

As will be apparent from Figure 2, in the particular example shown, the opposing brake component 60 includes a base portion 62 and an outer portion 61 , which also serves as a housing for the cord-handling unit.

The spool 40 and the rotatable brake component 50 are both configured to be rotatable about the winding axis A-A. In the particular example shown, this is accomplished by mounting the spool 40 on a shaft 64 provided by the base portion 62 of the opposing brake component 60 and by mounting the rotatable brake component 50 within an annular channel provided within the base portion 62 of the opposing brake component 60. However, this particular structure is not critical and it will be understood that other structural arrangements are suitable for enabling the spool 40 and the rotatable brake component 50 to rotate about the winding axis A-A.

As may also be seen from Figure 2, the outer portion 61 of the opposing brake component 60 includes a cord guiding feature 63, in which the cord 30 is slidably received. In the particular example shown, the cord guiding feature 63 is an aperture within the opposing brake component 60, and specifically within the outer portion 61 thereof; however, this is by no means essential and in other examples the cord guiding feature 63 could, for instance, be provided partially or wholly in another portion of the opposing brake component 60, such as the base portion 62 (for example, it could be provided partially in the base portion 62 and partially in the outer portion 62) and/or could be a slot or U-shaped feature.

In the particular arrangement shown in Figure 2, the opposing brake component 60 is also configured to be rotatable about the winding axis A-A. In the structure shown in Figure 2, this is accomplished by mounting the opposing brake component 60 (and specifically the base portion 62 thereof) on a shaft 22 provided by the anchor component 20. However, this specific structure is not critical and it will be understood that other structural arrangements are suitable for enabling the opposing brake component 60 to rotate about the winding axis A-A.

Attention is now directed to Figure 3, which is a perspective view of the cord-handling unit and anchor component 20 of Figure 2. Figure 3 displays clearly the position of the cord guiding feature 63. As will be appreciated, when the robot moves around the winding axis A- A, the cord 30 will be pulled by the robot. The cord 30 may, as a result, apply force to the cord guiding feature 63 of the opposing brake component 60 and thereby cause the opposing brake component to rotate about the winding axis A-A, with the cord guiding feature 63 therefore following the robot as it moves.

Reference is now directed to Figure 4, which is a perspective view of the anchor component 20 and the cord-handling unit Figure 2, with an outer portion 61 of an opposing brake component 60 removed so as to better illustrate other constituent parts of the cord-handling unit. The relative orientation of the spool component 40, the rotatable brake component 50 and the opposing brake component 60 is shown clearly in the drawing. As is apparent, the spool component 40 is mounted on the shaft 64 provided by the base portion 62 of the opposing brake component 60.

As is also apparent from Figure 4, the spool component 40 is mounted on the rotatable brake component 50. In the particular example shown, an axially-directed surface of a radially extending flange 44B at one end of the spool 40 contacts an oppositely axially- directed surface of the rotatable brake component 50. As also illustrated in Figure 4, the spool component 40 may include a further radially extending flange 44A at the opposite end of the spool 40, with the two flanges 44A, 44B being located on either axial side of a drum portion 43 of the spool, about which the cord 30 is wound.

Attention is now directed to Figure 5, which is a perspective view from below of the spool 40 of the cord-handling unit of Figure 2. The drawing illustrates the features of the spool 40 that interact with the rotatable brake component 50. In the particular example shown, these features are provided on an axially directed surface of radially extending flange 44B.

In more detail, the spool 40 includes a number of moveable elements 41 (1 ), 41 (2), which are each moveably mounted on the spool 40.

In the particular example shown, the moveable elements 41 (1 ), 41 (2) are each pivotably mounted on the spool 40. For example, they may be mounted such that they each pivot about respective axes parallel to the winding axis A-A (with these axes rotating about the winding axis A-A as the spool 40 rotates). However, pivotal mounting is by no means essential and, in other examples, the moveable elements 41 (1 ), 41 (2) could be slidably mounted in tracks (for example, radially oriented tracks) provided by the spool 40. Rotation of the spool 40 may cause each moveable element 41 (1 ), 41 (2) to move radially outwards relative to the winding axis A-A. For instance, each moveable element 41 (1 ), 41 (2) may be propelled radially outwards owing to centrifugal force. When the radial distance of any of the moveable elements 41 (1 ), 41 (2) is equal to or greater than a threshold radial distance (for instance, the distance to the edge of the flange 44B on which the moveable elements 41 (1 ), 41 (2) are mounted, as in Figure 5), a force is applied to the moveable element(s) in question. This force may oppose rotation of the spool 40 in the unwinding direction, which may, for example, slow the unwinding of the spool 40 and, ultimately, halt the unwinding of the cord 30 from the spool 40.

The forces opposing rotation of the spool 40 in the unwinding direction may result in a generally constant tension being applied to the cord 30 until the robot's fall from the window is halted. A braking mechanism applying such generally constant tension may, for example, impose a constant, relatively low force on the robot, which may reduce the risk of damaging the robot from bringing it to a sudden halt, while ensuring that the robot's fall is halted within a relatively short distance. Similarly, a low force may be imposed on the anchor component 20 and the cord, which may contribute to the longevity of the safety cord system as a whole.

As is also apparent from Figure 5, each moveable element 41 (1 ), 41 (2) is mechanically biased towards the winding axis A-A. In the particular example shown, this is accomplished by connected each moveable element 41 (1 ), 41 (2) to one end of a respective spring 42(1 ), 42(2), with the other end of the spring being coupled to the spool 40.

Regardless of the particular way in which the moveable elements 41 (1 ), 41 (2) are

mechanically biased, such mechanical biasing may, for example, generally oppose the centrifugal force. For instance, it may act to return the moveable elements to a respective initial radial position relative to the winding axis A-A. Hence, when the spool 40 is stationary, each moveable element 41 (1 ), 41 (2) may be located in its initial radial position. Further, the mechanical biasing may be designed so that the biasing force results in the braking mechanism being activated at a desired angular velocity value. For instance, the biasing force might be sufficient to ensure that the moveable elements 41 (1 ), 41 (2) move beyond the threshold radial distance only when the centrifugal force - and thus the angular velocity of the spool 40 - is greater than a desired value.

In some examples, the movement of any of the moveable elements 41 (1 ), 41 (2) beyond the threshold radial distance may result in those moveable elements contacting other components of the braking mechanism. Such components may, as a result, apply a force to the moveable elements 41 (1 ), 41 (2) that opposes the rotation of the spool 40 in the unwinding direction. A specific example of this is shown in Figure 6, which is a perspective view from above of the rotatable brake component 50 and the opposing brake component 60 of the cord-handling unit of Figure 2 (again, with the outer portion 61 of the opposing brake component removed for clarity).

In addition, Figure 6 illustrates the moveable elements 41 (1 ), 41 (2) that are mounted on the spool 40, as well as the springs 42(1 ), 42(2) that restrain the moveable elements; the spool 40 itself is not shown, so that these features may be seen.

More particularly, Figure 6 illustrates the moveable elements 41 (1 ), 41 (2) as having moved beyond the threshold radial distance discussed above. As is apparent from the drawing, this causes the moveable elements 41 (1 ), 41 (2) to contact other components of the braking mechanism. Specifically, the moveable elements engage with the rotatable brake component 50, which, in turn, causes the rotatable brake component 50 to co-rotate with the spool 40. As will be discussed in more detail below, the rotatable brake component 50 is configured such that it experiences a frictional force opposing such rotation.

As is shown in Figure 6 and Figure 7, the moveable elements may catch on portions of the rotatable brake component 50. More particularly, each of the moveable elements may engage with one of a number of retaining elements 51 (1 ), 51 (2) provided by the rotatable brake component 50. In the specific example shown in Figure 6 and Figure 7, these retaining elements 51 (1 ), 51 (2) are circumferentially arranged about the winding axis A-A.

As is shown in Figure 6, once a moveable element 41 (1 ), 41 (2) is engaged with one of the retaining features, that retaining feature may inhibit radial movement of the moveable element 41 (1 ), 41 (2) it is engaged with. A possible consequence is that once the braking mechanism is activated (by the engagement of the moveable elements 41 (1 ), 41 (2) with the rotatable brake component 50) it cannot easily be deactivated.

Reference is now directed to Figure 7, which is a perspective view from above of the anchor component 20, and the rotatable brake component 50 and the opposing brake component 60 of the cord-handling unit of Figure 2 (again with the outer portion 61 of the opposing brake component 60 removed for clarity). Figure 7 shows clearly the shape and orientation of the retaining elements 51 (1 ), 51 (2) of the rotatable brake. As is shown in Figure 7, each retaining feature may include a surface 52 for engaging with a corresponding surface on one of the moveable elements 41 (1 ), 41 (2). Hence, or otherwise, the retaining feature surface 52 may extend in the unwinding direction with increasing radial distance from the winding axis A-A, as illustrated in Figure 7.

As is further shown in Figure 7, the moveable elements 41 (1 ), 41 (2) and retaining features 51 (1 ), 51 (2) may have complementary shapes. In the particular example shown in Figure 6 and Figure 7, each moveable element 41 (1 ), 41 (2) includes a notch, which is shaped to receive a retaining feature 51 (1 ), 51 (2).

As noted briefly above, the co-rotation of the rotatable brake component 50 with the spool 40 (which results from the engagement of the moveable elements 41 (1 ), 41 (2) of the spool 40 with the retaining features 51 (1 ), 51 (2) of the rotatable brake component 50) causes the rotatable brake component 50 to experience a frictional force opposing such rotation. An example structure for providing this frictional force will now be described with reference to Figure 8, which is a perspective view of a cross-section taken through the cord-handling unit of Figure 2, again with the outer portion 61 of the opposing brake component 60 removed so as to better illustrate other component parts of the cord-handling unit.

In the example shown in Figure 8, portions of the rotatable brake component 50 and of the opposing brake component 60 are arranged in contact with each other so that rotation of rotatable brake component 50 relative to the opposing brake component 60 generates frictional forces opposing such rotation. Owing to the engagement of the spool 40 and opposing brake component 60, these frictional forces also oppose rotation of the spool 40 relative to the opposing brake component 60. In more detail, as shown in Figure 8, the rotatable brake component 50 and the opposing brake component 60 may each include a number of frictional surfaces. As illustrated in Figure 8, the frictional surfaces of the rotatable brake component 50 may contact the frictional surfaces of the opposing brake component 60 so as to provide the frictional force opposing relative rotation of the components. In designing such a cord-handling unit 10, the number of frictional surfaces may be varied in order to provide a specific frictional force. In addition, or instead, a range of different materials may be tested for the frictional surfaces in order to provide a specific frictional force. Moreover, the frictional surfaces of the rotatable brake component 50 could be formed of the same material(s) as the frictional surfaces of the opposing brake component 60, or of different material(s)).

In the particular example illustrated in Figure 8, the frictional surfaces are provided by respective sets of brake pads 55, 65 for each of the rotatable brake component 50 and the opposing brake component 60.

The structure shown in Figure 8 is an example of a structure where the rotatable brake component 50 and the opposing brake component 60 each provide a plurality of frictional surfaces that are arranged parallel to one another. This may provide a substantial amount of friction in a compact structure. As is shown in Figure 8, the frictional surfaces may, for example, be oriented such that they are each substantially normal to the winding axis A-A. Again, this may provide a substantial amount of friction in a compact structure.

The shapes of the brake pads of the example shown in Figure 8 are shown clearly in Figure 9, which is a is a perspective view from above of the brake pads, with the main portions of the rotatable and opposing brake components 50, 60 removed for clarity. As may be seen, each of the brake pads is substantially annular in shape.

The rotatable brake component 50 and the opposing brake component 60 may be biased towards one another so that their respective frictional surfaces are pressed together. As illustrated in Figure 8 and Figure 9, this may be accomplished by providing a wave spring 70 beneath the brake pads that provide the respective frictional surfaces. This wave spring 70 is shown clearly in Figure 10, which is a perspective view from below of the brake pads of the rotatable brake component 50 and the opposing brake component 60 of the cord- handling unit of Figure 2.

In designing a cord-handling unit 10, where the rotatable brake component 50 and the opposing brake component 60 are biased towards one another so that their respective frictional surfaces are pressed together, the strength of the biasing may be varied so that the cord-handling unit provides a desired frictional force. For instance, where the biasing is provided by a spring, such as a wave spring as shown in Figure 10, the amount of compression and the spring constant of the spring may be varied to provide a suitable biasing force.

In some examples, the frictional force provided by the cord-handling unit may vary as ΝΡμ, where N is the number of pairs of frictional surfaces (one surface of each pair being provided on the rotatable brake component 50 and the other on the opposing brake component 60), i.e. the number of pairs of brake pads, where brake pads are used, F is the biasing force, and μ is the coefficient of friction corresponding to the materials of the frictional surfaces. Thus, any of these factors may be varied during the design of the cord-handling unit 10 in order to achieve a desired frictional force.

Attention is now directed to Figure 1 1 , which is a perspective view from above of the anchor component 20 of Figure 2. The anchor component 20 may, as shown in Figure 1 1 , include a suction cup. In the particular example shown, the anchor component 20 also includes a tab 21 for assisting in disengaging the suction cup and removing the anchor component 20 from the window.

While in the example shown in Figures 6-1 1 the force applied to the moveable elements 41 (1 ), 41 (2) results from friction between the rotatable brake component 50 and the opposing brake component 60, it should be understood that this is not essential. Hence, a number of other structures for the breaking mechanism may make use of friction between components co-rotating with the spool and components not co-rotating with the spool. In one specific example, the spool may engage with a ring-shaped structure, which extends circumferentially around the spool. This ring-shaped structure may co-rotate with the spool relative to housing, with friction being generated between the ring-shaped structure and the housing as a result, which gradually halts the unwinding of the cord 30 and thus the fall of the robot.

Further, while in the example shown in Figures 6-1 1 when the moveable elements move beyond the threshold distance and contact other components of the braking mechanism, those other components apply a force to the moveable elements that results from friction between one or more components co-rotating with the spool and one or more components not co-rotating with the spool, this is by no means essential. Hence, in other examples, once contact has been made between the moveable elements and other components of the braking mechanism, rotation of the spool may prevented substantially immediately thereafter.

In one specific example, when the radial distance of any of the moveable elements is equal to or greater than a threshold radial distance, the moveable element(s) in question may contact a housing (or some other component) of the cord-handling unit. This housing may substantially prevent relative rotation of the spool thereafter. In such an example, the cord may have suitable elastic properties, so as to reduce the force applied through the cord and to the robot when the moveable members catch on the housing. Hence, the length of the cord may extend elastically in the process of halting the robot's fall from the window. A suitable elastic cord may, for instance, be capable of having its length extended by at least 20%, or perhaps more, such as, for example, at least 30% or at least 40% of its length. As an alternative (or in addition) to such an elastic cord, the end of the cord that is opposite to that secured to the spool might be attached to an elastically extensible element, such as a spring. This elastically extensible element thereby secures the cord to the robot 1 (or to the anchor component 20 in cases where the spool is secured to the robot). The length of the elastic element will then extend elastically in the process of the safety cord system halting the robot's fall from the window, so as to reduce the force applied through the cord and to the robot when the moveable members catch on the housing, as with the elastic cord.

To give a specific numerical illustration of how much the force applied to the robot is lessened by an elastic cord, consider a substantially inelastic cord catching a 2kg robot falling from a height of 3m. If the cord elongates by, for example, 1 % then the gravitational potential energy of the robot must be dissipated over a distance of 3cm. In this case, the gravitational potential energy is approximately 49J (E_p = mgh = 2kg x 9.8 ms^~2 x 3m) which, if dissipated over 3cm, equates to an average force of approximately 1600N (F = E_p/d = 49J/0.03m). Such a high force (1600N is equivalent to a mass of around 160kg hanging from the robot/anchor component) risks damaging the robot and/or detaching the anchor component from the window (in which case the safety cord system does not fulfil its inherent purpose). Moreover, the peak force applied by the inelastic cord will be even higher than 1600N. Furthermore, substantially inelastic cords may actually elongate by even less than 1 %, so the force applied to the robot will often be higher still than 1600N.

If, by contrast, an elastic cord is used, the gravitational potential energy may be dissipated over a much longer distance. At furthest extension, x, all of the gravitational potential energy has been converted into elastic potential energy and thus:

mg{h + x) = (Equation 1 ) Where k is the spring constant for the elastic cord. The force applied by the cord to the robot is greatest at the furthest extension x, where it is equal to kx. If the robot and anchor component can easily tolerate a maximum force F_max, then k = F_max/x. Substituting this expression into Equation 1 gives: mgh = x (^F_max - mg)

Which may be rearranged as: x = _n ^m9h _Λ (Equation 2)

Which, where F_max is taken to be 200N (equivalent to a mass of around 20kg handing from the robot/anchor component), for example, gives x ¾ 0.7m.

Depending on the particular setup that the user has (e.g. the size of the window, where the anchor is placed, how high above floor level the bottom of the window is), an extension of such a size may be inconvenient, as it may present a risk that in some cases (for example where the robot is working at a similar height to the anchor component) the robot will hit the floor, albeit it at a reduced speed, as a result of the elastic cord and braking mechanism.

By contrast, a safety cord system such as those described above with reference to Figures 1 -1 1 , where the braking mechanism applies a constant force through the cord to the robot may decrease the stopping distance by a factor of up to 2, as compared with braking mechanisms that rely only on elastic cords or elastic elements, such as springs.

Specifically, the energy dissipated by the braking force, which is constant and equal to F_max, over the stopping distance, d is, is equal to the gravitational potential energy, E_p, and thus: mg(h + d) = F_maxd (Equation 3)

Which may be rearranged as: If, as before, F_max is taken to be 200N, for example, Equation 4 gives d « 0.3m. It will be noted that this is significantly less than the value of 0.7m for the case discussed above, where the braking mechanism has an elastic cord or element.

Further, by dividing Equation 4 by Equation 2, it is possible to determine an expression for the ratio of the maximum extension, x, for a braking mechanism with an elastic cord or elastic element that applies a maximum force equal to F_max, to the stopping distance, d, for braking mechanism with a constant force of F_max. Thus: d { πιαχ - mg)

This may be rearranged as:

X mg

= 2 +^■

d { πιαχ - mg)

Where F_max > 2mg (which is true in many cases, since the braking force will often be much greater than the weight of the robot, so as to halt the robot's fall within a reasonable distance), then:

x

Thus, with a braking mechanism with a constant force of F_max, the stopping distance will in many cases be decreased by a factor of at least 2 as compared with a braking mechanism with an elastic cord or elastic element that applies a maximum force equal to F_max.

In addition, safety cord systems where the braking mechanism applies a constant force through the cord to the robot may experience little or none of the "bouncing" of the robot about the extended position of the cord that may occur with braking mechanisms that rely only on elastic cords or elastic elements, such as springs.

Considering now a different facet of the example cord-handling unit shown in Figures 6-1 1 , while in that example the movement of the moveable elements beyond a threshold radial distance resulted in the moveable elements contacting other components of the braking mechanism, with those other components applying a force to the moveable elements that opposes rotation of the spool in the unwinding direction, other examples may not rely on contact between the moveable elements and other components of the braking mechanism. In a specific example, the force applied to the moveable elements might be a magnetic or electromagnetic force; for instance, a ring of magnets could be provided around the winding axis, with the moveable elements interacting with these magnets once they move beyond the threshold radial distance.

Still further, it should be appreciated that other examples of a safety cord system may include more than one anchor component. Such an example is shown in Figure 12, which is a view from behind of a window-cleaning robot attached to a window by an in-built attachment system, as well as by a safety cord system according to a further example embodiment. The example embodiment of Figure 13 is generally similar in design to that of Figure 1 , but includes two anchor components: a first anchor component 20 and a second anchor component 25.

As may be seen, the first anchor component 20 has a cord-handling unit coupled thereto, which may be of similar design to that discussed above with reference to Figures 2-10. Thus, the cord-handling unit may include a spool 40 (not visible in Figure 12) that is configured to automatically rotate about a winding axis in a winding direction, with the cord 30 thereby being wound around the spool 40. As before, this may reduce the risk of the robot becoming entangled in loose cord, which might reduce the efficiency of the robot or cause the robot to fall off the window 1000.

As is apparent from Figure 12, the cord 30 extends from a first end, which is secured to the spool 40 within the cord-handling unit 10, to a second end, which is secured to the second anchor component 25. This may be contrasted with the embodiment of Figure 1 , where the second end of the cord is secured to the robot 1. As may also be seen from Figure 12, the robot is slidably coupled to the cord.

In more detail, the slidable coupling of the robot to the cord may, as shown in Figure 12, be achieved with a second cord. This second cord may extend from a first end to a second end, with the first end being slidably coupled to the first cord (e.g. using a ring through which the first cord passes) and the second end being securely coupleable to the robot.

In other examples, the second cord could be omitted, with the robot being slidably coupled to the first cord more directly, for example using a ring secured to the robot through which the first cord passes.

It should be understood that, regardless of the particular way in which the robot is slidably coupled to the first cord, in part as a result of the provision of two anchor components, the safety cord system of Figure 12 may halt the robot's fall before it has fallen a significant distance. Hence, the risk that the robot hits the floor may be lessened.

While in the particular example embodiments of Figures 1 -12 the anchor components are configured to be attached to the surface of the window 1000 (and therefore include suction cups), it should be understood that this is by no means essential. Thus, in other examples, anchor components may be configured to be coupled to another part of the window, such as the frame of the window 1001 and may, for instance, include flanges or clamps. In still other examples, anchor components may be configured to attach to an area adjacent the window, such as a wall, curtain rail, blind etc. and may, for instance, include suction cups, flanges, clamps, hooks, or any suitable anchor component.

Further, it may be noted that, in the particular example embodiments described above with reference to Figures 1 -12 the cord handling unit is configured to be rotatably coupled to the anchor component (or the robot), such that it rotates about an axis perpendicular to the window surface, with this axis being the same as the winding axis. However, it should be understood that it is by no means essential that the winding axis be the same as the axis of rotation of the cord handling unit. In other examples, the winding axis could, for example, be perpendicular to the axis of rotation of the cord handling unit and, as a result of the rotation of the cord handling unit, rotate about the axis of rotation of the cord handling unit. Turning now to Figure 13, there is shown schematically an example of a window-cleaning robot 1 , which may be utilised with the safety cord system described with reference to Figures 1 to 12, and details the systems included therein. The robot 1 and the safety cord system may together form a robotic window-cleaning system.

As is shown in Figure 13, the example of a robot 1 includes: a movement system 400, for moving the robot over the surface of the window; a navigation system 300, to enable to robot to navigate around the surface of the window; an attachment system 600, to enable the robot to attach itself to the window surface (and to keep it attached thereto); a cleaning system 500, for removing dirt, debris and the like from a portion of the window surface adjacent the robot, as the robot moves over the window surface; a power system 200, for powering the various systems, components etc. within the robot; a control system 1 10, for communicating with and controlling the systems of the robot; and a user interface 700, enabling the user to input commands, information and the like to control the robot's operation and providing an indication to the user of the robot's current state.

The control system 1 10 may, for example, include a main board, and all electronics, as hardware, software and combinations thereof and other components, necessary for the robot 1 to perform all of its operations and functions (known as the main board electronics). The main board includes one or more processors as part of the main board electronics.

As indicated in the drawing with solid lines, the navigation, movement, attachment, cleaning, power and user interface systems are in data communication with the control system, so that the control system can receive data from and/or send instructions to these systems.

The power system 200 may, for example, include: an internal power supply, including one or more batteries (typically rechargeable); battery voltage sensors, typically for each battery, that enable the robot to determine when the power supply is running low; and charging contacts, that enable electrical connection to an external power source so as to allow the internal power supply to be charged. The charging contacts may be connectable to an electrical lead that is connectable, for instance with standard plug, to an external power supply, such as a mains power supply; the lead may include a transformer, where appropriate.

As discussed above, the power system 200 may have a data connection to the control system 1 10 so that the control system can receive data from the power system, for example relating to the current power level of the internal power supply (e.g. using battery voltage sensors).

The robot 1 may be designed such that it can be received by a docking station (not shown) which the robot 1 will return to once its task is complete (e.g. for orderly control and arrangement of the robot), and/or when its internal power supply is running low. While in this docking station, various functions can occur, such as battery recharging (e.g. by means of charging contacts) and the like.

The power system 200 may, instead of having an internal power supply (or in addition to having an internal power supply) rely on power from an external power supply, such as the mains power supply. Where the power system relies solely on power from an external power supply, charging contacts may not be included, but the power system 200 may nonetheless include an electrical lead connectable to an external power source; such an electrical lead may be built-in to the robot 1 , so that it cannot be removed by the user and will not detach during normal operation.

As shown by dotted lines in Figure 13, the power system is electrically connected to the control, navigation, movement, cleaning and attachment systems, and the user interface, so as to supply electrical power to these systems and their components.

The navigation system 300 may include a number of sensors that enable the robot to navigate around the surface of the window, when moving using the movement system 400. For instance, the navigation system 300 may include: sensors that enable the robot to determine its current distance from the window frame (which will typically extend

perpendicular to the window surface); sensors that enable the robot to detect the presence of the window surface adjacent a portion of the robot; sensors that enable the robot to determine its current orientation (e.g. with respect to gravity or a predetermined orientation). As shown in Figure 13, the navigation system 300 is in data communication with the control system 100. The control system 100 may therefore receive data from the navigation sensors and control the movement system 400 in dependence upon such data.

As discussed above attachment system 600 may, for example, utilise suction forces to attach the robot to the window surface. Accordingly, it may, for instance, include one or more vacuum pumps to provide a suction force and one or more sealing members that contact the window surface so as to seal a space between the robot and the window surface, with the vacuum pump(s) being configured to reduce the air pressure in this space.

The attachment system 600 might instead (or in addition) utilise magnetic forces to attach the robot to the window surface. Accordingly, the user may be provided with a paired device that is placed on the opposite surface of the window to the side on which the robot operates, with the robot and the paired device being magnetically attracted to each other. Hence, the robot and/or the paired device may, for instance, include one or more magnetic members, such as electromagnets or permanent magnets.

As shown in Figure 13, the attachment system 600 is in data communication with the control system 100 and may therefore receive commands from the control system 100 and send status information to the control system 100. For example, the control system 100 may command the attachment system 600 to increase the attachment force.

The movement system 400, as noted above, enables the robot to move over the surface of the window. Accordingly, it may, for instance, include wheels, tracks and the like that contact the window surface and apply a force thereto so as to drive the robot over the window surface. As shown in Figure 13, the movement system 400 is in data

communication with the control system 100 and may therefore receive commands from the control system 100. For example, the movement system 400 may be commanded by the control system to move the robot along a path calculated by the CPU within the control system 100.

In some arrangements, the movement 400 and attachment 600 systems may be combined, such as where a number of elements each provide a separate attachment force and are moveable with respect to each other. One example of such a combined attachment and movement system is where two or more separate sealing elements are provided that are moveable with respect to each other; each of the sealing elements may be provided with a dedicated vacuum pump in such a situation.

The cleaning system 500, as noted above, removes dirt, debris and the like from a portion of the window surface adjacent the robot, as the robot moves over the window surface, using the movement system 400. The cleaning system may include, for example, a cleaning pad that is wetted with cleaning fluid, a reservoir for cleaning fluid, a water hose. Although in Figure 13 the cleaning system 500 is shown as being in electrical communication with power system 120 and in data communication with control system 100, in some arrangements, the cleaning system might include no powered components, in which case, such connections to the power 200 and control 100 systems would be unnecessary. In some arrangements, the cleaning system 500 may be combined with the attachment system 600, for example, where a suction force is applied through a cleaning pad. In further arrangements, the cleaning 500, attachment 600 and movement 400 systems might all be combined, for example where a number of cleaning pads are provided that may move relative to one another, with a suction force being applied through each cleaning pad.

Turning now to the user interface 700, as noted above, this may enable the user to input commands, information and the like to control the robot's operation and may provide an indication to the user of the robot's current state. Accordingly, it may include a number of controls, such as buttons, dials and the like, and a number of indicators, such as a display screen, LEDs and the like, or a combination of both, such as a touchscreen. It may also include a wireless communication link, so as to connect with a user device, such as a smart- phone, tablet device, laptop, PC etc.

As shown in Figure 13, the user interface 700 is in data communication with the control system 100. The user interface 700 may therefore receive status information from the control system 100 that it then displays or indicates to the user. Conversely, the control system 100 may receive user commands that are inputted using the user interface 700 and may, thereafter, send corresponding commands, for instance, to the movement 400, attachment 600 and cleaning 500 systems. For example, the user may use the user interface 700 to select one of a number of operation modes that the robot (specifically the control system 100) has been programmed with and the control system 100 may thereafter command, for instance, the movement 400, attachment 600 and cleaning 500 systems in accordance with rules and procedures that are associated with the mode selected by the user.

It should be noted that the window-cleaning robot 1 detailed above with reference to Figure 13 is merely an example of a window-cleaning robot that is suitable for use with the safety cord system described with reference to Figures 1 to 12: it is envisaged that other window- cleaning robots may be utilised.

More generally, it should be understood that the examples of robotic window cleaning systems and safety cord systems presented above are merely illustrative and that a wide variety of variations and modifications of such examples are possible without departing from the principles of the present invention.

Claims

1 . A safety cord system for a window cleaning robot, the system comprising:

a cord; and

a cord-handling unit, which is configured to be coupled to one of the anchor component and the robot and which comprises:

2. The safety cord system in accordance with Claim 1 , wherein the spool is

mechanically biased so as to wind the cord around the winding axis.

3. The safety cord system in accordance with any one of the preceding claims, wherein a cord guiding feature, in which the cord is slidably received, is provided within the cord handling unit, preferably wherein the cord guiding feature is configured as an aperture in the cord-handling unit, more preferably wherein the aperture is provided in the exterior surface of the cord handling unit.

4. The safety cord system in accordance with any one of the preceding claims, wherein the cord handling unit is configured to be rotatably coupled to said one of the anchor component and the robot, such that it rotates about an axis perpendicular to the window surface.

5. The safety cord system in accordance with Claim 4, wherein said axis perpendicular to the window surface is the winding axis.

6. The safety cord system in accordance with any one of the preceding claims, wherein the braking mechanism comprises at least one moveable element, each of which is moveably mounted on the spool, whereby rotation of the spool about the winding axis causes the moveable element in question to move radially outwards relative to the winding axis; and wherein ,when the radial distance of any of the moveable elements is equal to or greater than a threshold radial distance, a force is applied to the moveable element(s) in question, the force opposing rotation of the spool in the unwinding direction.

7. The safety cord system in accordance with Claim 6, wherein said forces opposing rotation of the spool in the unwinding direction result in a generally constant tension being applied to the cord until the robot's fall from the window is halted.

8. The safety cord system in accordance with Claim 6 or Claim 7, wherein each moveable element is pivotably mounted on the spool.

9. The safety cord system in accordance with any one of claims 6 to 8, wherein each moveable element is mechanically biased towards the winding axis.

10. The safety cord system in accordance with any one of claims 6 to 9, wherein, when the radial distance of any of the moveable elements is equal to or greater than a threshold radial distance, the moveable element(s) in question contact(s) one or more other components of the braking mechanism, said one or more other components applying said force to the moveable element(s) in question.

1 1 . The safety cord system in accordance with any one of claims 6 to 10, wherein the force applied to the moveable element results from friction between one or more

components co-rotating with the spool and one or more components not co-rotating with the spool.

12. The safety cord system in accordance with any one of claims 6 to 1 1 , wherein the breaking mechanism further comprises a rotatable brake component, which is configured such that it can rotate about the winding axis; wherein, when the radial distance of any of the moveable elements is equal to or greater than the threshold radial distance, the moveable element(s) in question engage(s) with the rotatable brake component, thereby causing the rotatable brake component to co-rotate with the spool, the rotatable brake component being configured such that it experiences a frictional force opposing such rotation.

13. The safety cord system in accordance with Claim 12, wherein the rotatable brake component comprises a plurality of retaining features that are circumferentially arranged about said winding axis, the retaining features being arranged such that, when the radial distance of any of the moveable elements is equal to or greater than the threshold radial distance, the moveable element(s) in question engage(s) with one of the retaining features.

14. The safety cord system in accordance with Claim 13, wherein, once a moveable element is engaged with a retaining feature, the retaining feature in question inhibits radial movement of the moveable element in question.

15. The safety cord system in accordance with Claim 13 or Claim 14, wherein each retaining feature includes a surface for engaging with a corresponding surface on one of the moveable elements, the retaining feature surface extending in the unwinding direction with increasing radial distance from the winding axis.

16. The safety cord system in accordance with any one of claims 13 to 15, wherein the moveable elements and retaining features have complementary shapes.

17. The safety cord system in accordance with any one of claims 12 to 16, wherein the breaking mechanism further comprises an opposing brake component, the rotatable brake component and the opposing brake component being arranged in contact with each other such that rotation of rotatable brake component relative to the opposing brake component generates frictional force opposing such rotation.

18. The safety cord system in accordance with Claim 17, wherein the rotatable brake component and the opposing brake component each include at least one frictional surface, the frictional surface(s) of the rotatable brake component being in contact with the frictional surface(s) of the opposing brake component so as to provide the frictional force opposing relative rotation of the components; and wherein the rotatable brake component and the opposing brake component are biased towards one another so that their respective frictional surfaces are pressed together.

19. The safety cord system in accordance with Claim 18, wherein the rotatable brake component and the opposing brake component each include a plurality of said frictional surfaces, the frictional surfaces being arranged parallel to one another, preferably wherein each frictional surface is substantially normal to the winding axis.

20. The safety cord system in accordance with any one of claims 17 to 19, when dependent upon Claim 3, wherein the cord guiding feature is provided within the opposing brake component, preferably wherein the cord guiding feature is provided in an outer portion of the opposing brake component.

21 . The safety cord system in accordance with any one of claims 17 to 20, wherein the opposing brake component is configured such that it can rotate about the winding axis.

22. The safety cord system in accordance with any one of claims 6 to 10, wherein the cord-handling unit further comprises a housing;

wherein, when the radial distance of any of the moveable elements is equal to or greater than a threshold radial distance, the moveable element(s) in question contact(s) the housing, the housing substantially preventing relative rotation of the spool thereafter.

23. The safety cord system in accordance with Claim 22, wherein the cord is elastic, its length extending elastically in the process of halting the robot's fall from the window.

24. The safety cord system in accordance with Claim 22 or Claim 23, wherein the second end of the cord is connected to an elastically extensible element, which is configured to be secured to said other of the anchor and the robot, thereby securing the cord to said other of the anchor and the robot, the length of said elastic element extending elastically in the process of halting the robot's fall from the window;

preferably wherein said elastic element comprises a spring.

25. The safety cord system in accordance with any one of claims 22 to 24, when dependent upon Claim 3, wherein the cord guiding feature is provided within the housing.

26. The safety cord system in accordance with Claim 22 or Claim 25, wherein the housing is configured such that it can rotate about the winding axis.

27. The safety cord system in accordance with any one of the preceding claims, wherein the anchor component comprises a suction cup.

28. The safety cord system in accordance with any one of the preceding claims, wherein the cord-handling unit is coupled to the anchor component and further comprising a second anchor component, the second anchor component being coupleable to, or adjacent to, the window, the second end of the cord being secured at said second anchor component;

wherein the robot is slidably coupleable to the cord.

29. The safety cord system in accordance with Claim 28, further comprising a second cord, extending from a first end to a second end, the first end being slidably coupled to the first cord, the second end being securely coupleable to the robot, the robot thereby being slidably coupled to the first cord.

30. The safety cord system in accordance with any one of the preceding claims, wherein the second anchor component comprises a suction cup.

31 . A robotic window-cleaning system comprising a window-cleaning robot coupled to the safety cord system in accordance with any one of the preceding claims.