GB2548349A

GB2548349A - Cable robot movement system using adjustable supports

Info

Publication number: GB2548349A
Application number: GB1604272.3A
Authority: GB
Inventors: Mercanti Jakob
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-03-13
Filing date: 2016-03-13
Publication date: 2017-09-20
Anticipated expiration: 2036-03-13
Also published as: GB2548349B; GB201604272D0

Abstract

A cable robot system may be used to clean a building. The system may comprise a central element 1 connected to a plurality of cables 2 which may be connected to a plurality of winches or pulleys 3 located at the edges or corners of a building. The central element may be steered or guided around the face of the building by selectively operating the winches to shorten or lengthen cables 2 and by use of an intermediate wheel like support 5 that is located on each of the cables. The central support means may have a telescopic arm (1, Fig 5) and may be fitted with a pulley (7, Fig 2) or a winch means (6, Fig 3). The central element may be fitted with repair and cleaning tools such a brushes and/or nozzles, and/or painting, plastering tools.

Description

Cable robot movement system using adjustable supports

The invention relates to a movement system based on the cable robot solution to move tools on a building fagade in order to carry out base maintenance operations like cleaning, painting and plastering.

The maintenance of a high rise building requires regular window cleaning from the outside and sporadic repainting or repointing of the building external walls. The most common way to carry out such operations is still based on human labour both using workers secured by ropes attached to the roof of the building or using platforms held by cables, those solutions are both risky for the workers and expensive due to the complex safety equipment and the specialized workforce involved. Several automatic devices (or robots) have been developed in recent years to carry out those tasks, in most of the cases those robots are sustained by ropes connected to the building roof. While this solutions work in principle some limitations have prevented those to be commercially viable because of some limitations. Irregular building shapes in modern architecture and the presence of additional features like balconies on the fagades prevent robots to carry out a satisfactory work reaching all the parts of the window to be cleaned, normally the cleaning robot operations are slower than human workers and finally the absence of additional supports other than the main connecting cable with the building makes the system prone to oscillations induced by wind with the critical danger or the device hitting and therefore damaging the window while oscillating.

The last point is especially critical because the cleaning operations are carried at high altitudes without any additional safety measure to protect the pedestrians. To apply the correct pressure between the washing tool and the windows normally additional features are added (like a fan to push the robot against the window or a device to create suction between the robot and the window) at the expense of the unit simplicity and weight. Moreover several available robots operate along a vertical line and require a repositioning to move horizontally, therefore the common praxis is to use a rotating brush with the same width of a series of windows, again increasing the weight and the dimensions of the device. Medium duty tasks like a fagade painting or plastering require at the moment the installation of a scaffolding or similar techniques to the ones mentioned for the manual window washing, in these cases buildings with limited access on one or more sides are presenting additional complications.

To overcome these limitations the proposed invention (or cable robot or system) uses a cable actuated central element connected to multip_e pick-up points which are preferably electro actuated winches fixed on specific points on the building fagade. By defining the length of the cables activating simultaneously the different winches it is possible to move the central element on the working plane (building fagade). To withstand load normal to the working plane the proposed device introduces additional movable supports which are independently driven along the main cables. Finally the central element can be equipped with a telescopic arm moving normally to the working plane.

The base system is well known (as cable robot) and guarantees an high resistance to loads parallel to the working plane and therefore allows high accelerations of the central element guaranteeing an higher speed with respect to traditional system connected with a single cable, the pick-up points can be placed in easy access locations like the lower building corners accessible from the ground level and the top corners accessible from the roof. Thanks to the freedom to move vertically and horizontally (for instance on the surface of the windows) a small single tool can be used to carry out the required operation. The movable intermediate supports are typically wheels and are introduced to transfer the load to robust portions of the building (for instance solid walls or window mounting frames), a separate driving system of the supports is necessary to allow an independent movement of the central element. The telescopic arm is capable of keeping the working unit (washing brush, water jet or paint or plaster jet) close to the working surface also in the case of irregular architectural shapes keeping always the optimal pressure between the tool and the working surface when required, this is possible thanks to the system additional stiffness normal to the plane coming from the intermediate supports. A reliable full automatic system can also operate during the night minimizing the maintenance impact.

The device will now be presented in detailed drawings:

Figure 1: general layout of the device mounted on the building fagade. Figure 2: detail of a single cable of figure 1 comprising the centra_ element, the two winches driving the main cable and the intermediate support (In this case a wheel).

Figure 3: variant of the support driving mechanism using a central sphere and one winch on each cable end.

Figure 4: load scheme of the system mounted in rest (solid line) and under a normal load (dotted line).

Figure 5: detail of the passive steering hub proposed to drive the wheels on the building fagade.

Figure 6: top view of the figure 5.

Figure 7: schematic view of a variant of the system using additional stabilizing fans on top of the intermediate supports.

Figure 8: schematic view of a top pick-up point (electro-actuated winch or pulley) mounted on a building roof and hold by a fillable water tank.

Figure 9: schematic view of a three degrees of freedom central element tip (one translation normal to the working plane and two rotations).

The proposed device is illustrated in figure 1 and comprises one central element (1) carrying the cleaning or painting equipment driven by multiple cables (2) connected to remotely driven winches (3) which can be placed on the boundary of the working area, the working area is typically a building fagade and the winches can be placed at each of the corners. The fixing points (or pick-up points) can be the accessible corners of the building (typically two corners at ground level reachable from the road and two top corners reachable from the roof); on every pick-up point either an electro-actuated winch or a return pulley connected ultimately to an electro-actuated winch can be mounted. By driving the winches and therefore extending or retracting the cables connecting it with the central element it is possible to move it on the working area (whole building fagade), since preferably three or more cables can be used to drive the central element the system is over constrained requiring the simultaneous movement of al_ the winches to define the central element trajectory. The winches can also be placed on the central element but this would increase its weight and therefore the system inertia. The pick-up points can be potentiaily mounted on rails, for example the top pick up point can be movable on the roof along a horizontal line, to further speed up the overali operations. Since the central element can be held by three or more cables at the same time it is defined as an over constrained system which is very stiff on the working plane being abie to react to each load component parallel to it, this feature combined with its iow inertia allows for high accelerations on the working plane potentially speeding up the cleaning or painting process without the danger of triggering dangerous oscillations, moreover this allows also the system to be stable towards wind components tangential to the working plane (side wind). The potentiai high speed in both verticai and horizontal directions can allow to use a compact tool, for instance to clean a window there is no need to use a brush as wide as the window itself as the moving system is abie to effectively reach every position on the window surface, in this way the system can potentiaily have a compact design and be easy to be dismounted and transported. Having a transportable system can reduce considerably the maintenance costs in opposition to the common soiution of using a cieaning platform permanently mounted on the building roof. The proposed solution is weil known in modern technoiogy and has been extensively tested and developed, one of the most known publications in the fieid is "Cable-Driven Parallel Robots" from Andreas Pott and Tobias Bruckmann (Aug 2014), in the book there is aiso an appiication study of the same principle on a building fagade (on the Media-Tic fagade in Barcelona) , also several patent requests are using the same principie for building maintenance (for instance JPHO6142011).

Even being a very stiff system on the working plane this iayout on its own is lacking almost any stiffness for load components normal to the working plane itself like normal wind loads, this is due to the very long cables used to drive the central element which are not able to transfer almost any of the load component normal to the working plane to the pick-up points (please refer to figure 4, in this case without the intermediate supports). Assuming indeed a maximum cabie tension allowed by the system the maximum sustainable normal load would be the cable tension loading multiplied by the sinus of the angie between the cable position and the working plane (again please refer to figure 4), since this component would be very small in the proposed appiication due to the very long cables used, this would inevitably lead to a bigger off plane movement of the central element which could ultimately hit the building fagade or the window. To solve this issue the proposed device is integrating intermediate supports (4) which can be wheels preferably steerable (please refer to figure 2) or spheres (please refer to figure 3, element 9) which travel on the building fagade together with the central element transferring the normal load to the fagade itself. The outboard pick-up points (winches) which are typically fixed and are laying on the building fagade are keeping every cable under tension, the tension is then transferred to the intermediate supports which are then pushed to the fagade surface. Whenever the central element which carries the payload and the relative equipment is loaded normally to the working plane (for instance because of strong wind normal to the building) the cable deforms and transfers the load to the intermediate supports (In figure 4 the unloaded scheme is displayed in solid line, the loaded and deformed condition in dotted line), as evident from the figure 4 the load components are now more favorable and for a given maximum cable tension the system is able to withstand a load normal to the building of almost the same magnitude. This is due to the bigger angle formed by the cable portion connecting the central element with the center of the intermediate support. If the load is applied normally to the working plane but in the outside direction (this can happen due to the inertial loads while the system is oscillating) an off-plane movement is allowed, this movement is not dangerous regarding possible clashes of the central element with the fagade, the intermediate supports can even lose contact with the fagade and regain it while the system is moving back towards the working plane acting as safety element to prevent the central element to impact on the fagade itself. Since the building fagade contains in most cases several windows, or generally speaking is characterized by regions of higher stiffness (for instance in a modern skyscraper where the windows mountings are located or simply solid walls) and regions of lower stiffness and critical fragility (typically the center of the windows) the proposed device integrates a driving system of the intermediate supports which can move along the direction of the main cable they are mounted on. The goal of this driving system is to be able to move freely the central element on the working plane via the mentioned winches (3) in order to carry out the assigned task while a second set of winches (6) will drive the intermediate supports (4 or 9) along the main cables keeping them on predefined areas of building facade high stiffness. A simple example of this solution is that the central element is cleaning a windows and therefore requires a defined path covering the whole window area while the additional driving system will keep the supports just outside of the window and in order not to damage it are transferring the load normal to the fagade to the solid wall around the window. The supports require an independent movement and are not rigidly connected to the central element as otherwise the supports could end up either in the window area or on one of the surrounding windows during the central element movement. There are several solutions to achieve this movement, one option displayed in figure 3 is to place one additional winch (6) on the central element (1) which is connected on the opposite end of the main cables (2) with respect to the main winch (3), by moving the winches at the same time it is possible both to define the length of the main cable in order to drive the central element and to move the intermediate support (9) attached to it along its axis independently from the central element movement. The second solution, illustrated on figures 1 and 2, is to place both the winches (3 and 6) on the boundary possibly one next to the other and use a pulley (7) on the central element for the cable return, the intermediate support (4) will be then connected to one of the cable halves and will be driven by the winches system similarly to what described in the previous solution. A proposed alternative to an active steering system of the wheels is illustrated in figures 5 and 6 and consists of an hub (8) which presents the hole (10) for the driving cable in an offset position, the central hub (8) is staying in a fixed position with respect to the wheel (4) because a ball bearing (12) is mounted between it and the wheel, finally the hub can rotate off the wheel plane thanks to an additional hinge (11) ; when the cable is driven along the working plane by a force (illustrated in figure 6) the wheel will follow and steer passively in the direction of travel because of the torque generated by the drag component with respect to the hub additional wheel (see figure 6 for reference).

Finally the proposed device will take advantage of system stiffness both on and off plane by adding a telescopic arm (5) moving normal to the working surface placed on the main central element (1) which will move the tool used for the building maintenance to the building surface. The telescopic arm can integrate an active control and a safety release which in case of an abrupt application of an off plane load (for instance a strong wind normal to the building fagade) will allow the telescopic arm itself to slide with respect to its base in order not to damage the building fagade or the window, while as previously described the intermediate supports will withstand the load transferring it to portions of the fagade capable of withstanding normal load, this feature is very important to guarantee the system safety preventing a clash between the arm tip and the window (or in general the fagade). The telescopic arm can keep the tip always close to the working surface both in case of geometrical features on the fagade and even in the case of slightly curved fagades, crucially the telescopic arm can apply a constant pressure between the tool and the working surface. The central element is rigidly connected to the different cables described in the document, if rotated along whichever axis the cable tension will bring it back to the base position (for instance if rotated along an axis normal to the working plane in torsion the corners of the central element would be pulled back to the original position by the cable tensions), nevertheless to improve the central element kinematics and in particular to define a pure translational movement additional cables can be added, those can also not be equipped with additional supports. The telescopic arm can also be equipped with a two degrees of freedom head (figure 9, element 18) capable of rotating along to normal axis with the goal of reaching also the portions of the fagade in an undercut region with a similar kinematics currently used in five axis cnc machines heads. The arm tip can be equipped with multiple tools commercially available to carry out basic operations, in order to clean windows and skyscraper facades those comprise but are not limited to spray equipment to jet high pressure water on the window surface to clean it, an automatic brush both single or composed by multiple brushed rotating along an axis normal to the working plane. If used to paint a building fagade this will include a spray nozzle which can also be protected by an enclosed chamber which would preferably be a cube having just the side facing the working surface open to have a good control of the painted area and prevent the paint both to reach undesired areas and to be nebulized in the air, this solution is advisable also because the system offers a very good stiffness parallel to the working plane allowing a fast and precise movement of the central element. The system can also be used to repoint an existing wall or to apply a new plaster using a commercially available automatic plastering technique using a nozzle, this can be a very interesting solution in the case of older buildings requiring new heat insulating plasters.

The system can be integrated into the building fagade moving the central element next to one of the pick-up points in resting position or can be mounted on the fagade only when a specific task is required. The pick-up points (winches or return pulleys) can are typically (but not limited to) four with two laying on the ground level with a quick and easy access and two on the building roof. The top pick-up points can be fixed directly on the roof (figure 8, 15) via a Z shaped bar (14) with one horizontal arm connected to a pulley or an electro-actuated winch (16),the other horizontal arm rigidly fixed to the roof, and a vertical or inclined arm connecting the two, this would prevent the workers mounting the system to have to access the building outer wall and the associated safety risks, finally the Z shaped bar can be held on the ground via a movable tank finable with water (17) once placed in position, this solution would avoid the need to drill fixing holes into the building roof with the tank carried in place empty and then filled with water once in working position holding the bar thanks to the increased weight. The working area does not need to be perfectly rectangular as in the displayed figures but can also be of an irregular shape, this would just require a different driving strategy of the several winches which can be implemented in the software driving the system. In order to further reduce oscillations normal to the working plane it is possible starting from the variant using wheels as movable supports, to use dampers which allow a limited movement of the cable normal to the working plane can be integrated into the design, since as already exposed the system will be always under tension the damper can effectively reduce oscillations in both directions of travel. To counteract loads normal to the working plane a different solution can also be integrated introducing one or more electro actuated fans (13) on the central element or on the movable supports, this solution is illustrated in figure 7. The fans can be actuated in order to directly counteract any gust of wind in the direction normal to the working plane (the system is inherently very stiff to the wind component tangential to the working plane as exposed). The use of active fans can also enable the intermediate supports (4) not to stay in constant contact with the building fagade by mounting the winches or pulley attachment points (3) slightly away from the facade, this is possible because it is not necessary to overcome the rolling resistance can indeed allow a much faster movement of the system.

Finally different variants of the described kinematics can also be introduced placing the connecting points (so winches or pulleys returning the cable from a winch) on a rail in order to be able to slide them along one or more sides of the building fagade, this solution would reduce the length of the cable used and allow a further degree of freedom of the system, potentially allowing a faster movement. The connecting point (3) distance from the building fagade can also be regulated when the system is installed, this feature coupled with the possibility of choosing intermediate supports of different sizes (for instance intermediate wheels of different radii) allows to overcome the obstacles included in the fagade, like a series of balconies or simple irregularities. A further variant can include an active control of the pick-up point distance to the facade which in combination to the built in possibility of adjusting the cable tension can define the force pushing the intermediate supports to the facade itself. The system can also be used to carry loads on a building fagade like replacement windows or generic building material, and can therefore bring a substantial improvement during the building process. This feature can be exploited also when a structural reinforcement of the building is required, it is possible indeed to place electro welded reinforcement nets on the outside of the building fixing them temporarily for instance with nails with a devoted equipment on the telescopic arm tool and to apply a layer of cement afterwards replacing the tool with a cement nozzle.

The telescopic arm tip can also be equipped with a camera in order to allow a remotely connected operator to drive precisely the central element on the working plane when a precise operation like repointing building cracks is required, the same solution can also be used to inspect details of the building fagade whenever required. The overal_ system can be driven automatically or directly by an operator using the mentioned camera.

Claims

1. Cable robot comprising a central element driven by cables and one or more intermediate supports which are movable along the cables independently from the movement of the central element.

2. Cable robot according to claim 1 in which the central element comprises a telescopic arm movable in a normal direction to the working area.

3. Cable robot according to claim 1 or 2 in which wheels are used as intermediate supports with the wheel hub being along the direction of the cable.

4. Cable robot according to claim 3 in which the wheels are steerable along an axis normal to the working plane.

5. Cable robot according to claim 4 in which the hub has the hole which allows the crossing of the driving cable in an offset position with respect to its center and having an additional hinge between it and the ball bearing connecting it to the wheel in order to steer passively the wheel.

6. Cable robot according to claim 3 in which the cable driving the central element is connected to a winch on one end and then passes through a pulley placed on the central element and finally is connected to a second winch on the other end, one of the cable halves Is connected to the intermediate support allowing via the movement of the winches both the central element and the support independent movement

7. Cable robot according to claim 1 or 2 in which a sphere is used as intermediate support.

8. Cable robot according to claim 7 in which the sphere is mounted in a housing allowing a rotation along each possible axis and the cables are connected to the external shell of the housing.

9. Cable robot according to claim 8 in which the sphere position along the cable axis connecting the OB pick-up point to the central element is defined by a winch mounted on the central element regulating the cable length between the sphere housing and the central element.

10. Cable robot according to claim 2 in which the tip of the telescopic arm is equipped with a rotating brush or a nozzle capable of jetting high pressure water on a window surface.

11. Cable robot according to claim 2 in which the tip of the telescopic arm is equipped a nozzle capable of jetting paint on the building fagade.

12. Cable robot according to claim 11 in which the paint nozzle is protected by a housing to direct the paint in a specific area on the plane .

13. Cable robot according claim 2 in which the tip of the telescopic arm is equipped with a nozzle capable of jetting previously mixed plaster on the building fagade.

14. Cable robot according to claim 2 in which the head of the telescopic arm is equipped with a two degrees of freedom head capable of rotating along to normal axis.

15. Cable robot according to any of the preceding claims in which the supports are driven by a winch placed on the support itself capable to moving the support relatively to the cable.

16. Cable robot according to claim 3 which integrates a damper on the wheel hub to reduce the system oscillation normal to the working plane .

17. Cable robot according to claim 1 or 2 which integrates one or more electro actuated fans placed on the central element or on one or more intermediate supports to produce a load normal to the working plane.

18. Cable robot according to claim 1 or 2 in which one or more cable pick-up point are placed on a device, like but not limited to a winch mounted on a rail, movable along one or more sides of the working plane .

19. Cable robot according to claim 1 or 2 but with pick-up points distance to the building fagade adjustable mechanically.

20. Cable robot according to claim 2 in which the telescopic arm tip is equipped with a camera capable of recording and sending images of the working surface.

21. Cable robot according to claim 3 in which the telescopic arm is equipped with a holding mechanism or robotic arm capable of carrying loads on the building fagade.

22. Cable robot according to claim 21 in which one or more nail guns are added to the telescopic arm tip to be able to temporarily fix electro welded nets to the building fagade.

23. Cable robot according to claim 1 or 2 in which the top pick-up points are fixed directly to the top roof plane via an Z shaped bar with one horizontal arm connected to a pulley or an electro-actuated winch, the other horizontal arm rigidly fixed to the roof, and a vertical or inclined arm connecting the two.

24. Cable robot according to claim 23 in which the horizontal arm connected to the building roof is hold in position by a fillable water tank.