FIELD OF THE INVENTION

[0001] This disclosure relates to apparatus and systems for autonomous and/or semi-autonomous performance of operations such as cleaning, inspection, maintenance, etc. of the outside of buildings, in particular, though not exclusively multi-story buildings. The disclosure also relates to methods of cleaning the outside of buildings using autonomous and/or semi-autonomous apparatus .

BACKGROUND OF THE INVENTION

[0002] Businesses owning or occupying multi-story buildings can pay large amounts of money to have their windows cleaned once or twice every year. Research indicates costs of around $15,000 per clean for a modest glass fagade office building of 7 stories. Working at height raises safety issues faced by window cleaners globally. Workplace health and safety is becoming increasingly significant with legislative changes and penalties for negligence and breaches being increasingly enforced. Financial and criminal penalties, including jail terms for grave violations, mean management is less inclined to place personnel in dangerous situations .

[0003] To minimize risks, expensive safety gear, associated infrastructure and insurance is required. These expenses drive up the costs of window cleaning and consequently reduce the frequency of building window cleans.

[0004] Autonomous and semi-autonomous systems have been proposed and implemented for cleaning high-rise building exteriors. In one implementation, marketed under the name Skypro, a large and bulky system akin to a carwash roller system is suspended from a roof anchor and rolls down the building, spraying a large amount of water and dislodging dirt and debris as it goes. The system is semi-autonomous, requiring no human presence at the cleaning interface, but requires an operator and, due to the large size of the unit, typically requires multiple people to install. In addition, because the system uses lots of water which is not recaptured and because there is no drying system, the system must use reverse osmosis water to prevent streaks and to prevent any environmental contamination.

[0005] Smaller autonomous solutions have been proposed. These often use suction cups or similar for attaching to the building surface while a system of brushes or wipers clean the surface. Suction cup systems have not proven effective because suction cups lose their suction properties over time, can leave marks and often have awkward control systems. These systems, requiring a permanent attachment to the building, are not well suited to handling various building surface structures such as mullions that divide the windows and floors.

[0006] A small financially competitive autonomous or semi- autonomous mechanical window cleaner that can deal with a variety of building styles would address many of these issues.

SUMMARY OF THE INVENTION

[0007] An autonomous device for cleaning or otherwise engaging with the outside of buildings includes a vehicle that is suspended from and tethered to a positioning system secured to the building above the vehicle. The vehicle sends positioning signals to the positioning system to maneuver the vehicle, e.g. up/down and left/right over a panel of the building within the confines of a border of the panel while components of the vehicle engage with the building to perform one or more operations. For example, the components may be cleaning components for cleaning a window of the building. When the panel operation is complete, vertically disposed propellers are activated to push the vehicle off the building while the positioning system simultaneously positions the vehicle over the next target panel. The propellers allow the vehicle to clear mullions and similar dividers.

[ 0008 ] In one aspect of the disclosure, there is provided a system for performing servicing the exterior of a building, the system including a vehicle and a positioning system for positioning the vehicle. The vehicle may include one or more servicing components for performing one or more operations on one or more panels of the building, one or more first propellers mounted, in use, in a vertical plane and configured to generate thrust away from a vertical building surface, and one or more tether anchor points. The position system may be configured to be secured to a building and may include a tethering arrangement including at least one tether for tethering the vehicle below the positioning system, a lateral movement system for providing lateral movement of the vehicle via the at least one tether, and a lifting arrangement for providing vertical movement of the vehicle via the at least one tether.

[ 0009 ] In one aspect of the disclosure, there is provided a cleaning vehicle for use on an exterior of a building, the cleaning vehicle including one or more cleaning components, one or more propellers mounted, in use, in a vertical plane and configured to generate thrust away from a vertical building surface, and one or more tether anchor points for tethering the cleaning vehicle in suspension from a positioning system.

[ 0010 ] In one aspect of the disclosure, there is provided a method for cleaning a vertical surface of a building including a plurality of panels separated by one or more dividers using a cleaning vehicle including one or more cleaning components and one or more first propellers. The method may include suspending the cleaning vehicle from a positioning system by at least one tether in alignment with a first panel of the plurality of panels, executing a panel cleaning routine to maneuver the cleaning vehicle across the first panel by the positioning system while activating the one or more cleaning components, executing a panel jump routine to move the cleaning vehicle from the first panel to a next target panel including maneuvering the cleaning vehicle into alignment with the next target panel by the positioning system, and simultaneously operating one or more of the first propellers to propel the cleaning vehicle away from the building to provide clearance over the one or more dividers between the first panel and the next target panel, and re- executing the panel cleaning routine for the next target panel.

[ 0011 ] In one aspect of the disclosure, there is provided a method for servicing a vertical surface of a building including a plurality of panels separated by one or more dividers using a vehicle including one or more servicing components and one or more first propellers . The method may include suspending the vehicle from a positioning system by at least one tether in alignment with a first panel of the plurality of panels, executing a panel servicing routine to maneuver the vehicle across the first panel by the positioning system while activating the one or more servicing components, executing a panel jump routine to move the vehicle from the first panel to a next target panel including maneuvering the vehicle into alignment with the next target panel by the positioning system, and simultaneously operating one or more of the first propellers to propel the vehicle away from the building to provide clearance over the one or more dividers between the first panel and the next target panel, and re-executing the panel servicing routine for the next target panel .

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Reference will now be made, by way of example only, to specific embodiments and to the accompanying drawings in which :

[0013] Fig. 1 schematically depicts a building servicing system in front view;

[0014] Fig. 2 schematically depicts the building servicing system in side view;

[0015] Fig. 3 is a front perspective of an embodiment of a servicing vehicle;

[0016] Fig. 4 is a rear perspective of the servicing vehicle of Fig. 3;

[0017] Fig. 5 depicts a rear view of the servicing vehicle of Fig. 4 with a framework removed;

[0018] Fig. 6 depicts a system for driving wheels of servicing vehicle;

[0019] Fig. 7 depicts an embodiment of a positioning system;

[0020] Fig. 8 depicts an embodiment of the slider, winch and tether arrangement;

[0021] Fig. 9 depicts the positioning system of Fig. 8 supporting a servicing vehicle;

[0022] Fig. 10 schematically depicts an embodiment of the on-board electronics of a servicing vehicle;

[0023] Fig. 11 shows a flowchart of a method for cleaning a building panel; and

[0024] Fig. 12 schematically depicts a cleaning pattern. DETAILED DESCRIPTION OF THE INVENTION

[ 0025 ] The present application relates to a vehicle that can be used to service the exterior of a building to perform one or more operations. Specific reference will be made to a cleaning vehicle that can be used to clean windows of the building. However, other services and operations will be apparent to the person skilled in the art. The focus of the system and devices to be described is the ability of the vehicle to engage with the panels of the building, e.g. windows, maneuver across the panel to perform the required operation or service, and then safely traverse mullions or similar dividers when moving from one panel to the next. The focus is not considered to be the particular operation that is performed on the panel .

[ 0026 ] A window cleaning robot system that can effectively wash and dry high rise glass windows with minimal need for soaps or other chemicals is to be described. The cleaning system effectively maneuvers around building segments by being able to cross mullions, sense crosswind and compensate accordingly. It requires minimal human interference once initially set up.

[ 0027 ] One of the issues that an autonomous cleaning system must contend with is to cross a significant protrusion from the building. A very large percentage of buildings have mullions or similar protrusions between floors and window panes, so being able to cross these dividers is necessary for a cleaning vehicle to be able to clean a broad range of buildings.

[ 0028 ] In addition, an autonomous cleaning system should be stable in, and able to compensate for, cross winds. The ability to account for variable wind conditions enables the system to operate in a wide range of weather conditions, increasing productivity and cost effectiveness. [0029] The window cleaning system uses a window cleaning vehicle or device that is tethered to and suspended from a positioning system that is located above the vehicle. In one embodiment, the positioning system is anchored at the roof of the building. The positioning system controls the height and lateral position of the cleaning vehicle relative to the building exterior. The positioning system may operate under control signals from the cleaning vehicle. Further details of the positioning system will be described in more detail below.

[0030] When the cleaning device needs to traverse a mullion or similar structure, the window cleaning device uses quadcopter style motors and propellers to generate thrust in the lateral plane pushing the device out away from the building pivoting on its tether from the top of the building.

[0031] A further range of quadcopter technology is used including flight stabilization and speed control. Both the thrust rotors and control and stabilization rotors operate to position the device in the vertical plane, rather than the horizontal plane that quadcopter technology is typically used for .

[0032] Once suspended a suitable distance off the building's side the positioning system moves the cleaning device across the mullion. When on the far side of the mullion the thrust off propellers turn off and the cleaning vehicle recontacts the window. To improve cleaning efficacy an opposing set of propellers pushes the device onto the window when the clean is under way.

[0033] Existing mechanical cleaning systems can not actively compensate for cross wind. The ability to do so allows this product to operate in a wider range of weather conditions, increasing productivity and cost effectiveness. The device compensates for wind firstly through the use of an anemometer mounted to detect cross winds which is passed to the program for processing and then by the propellers of the device tilted accordingly .

[0034] An embodiment of a cleaning system is depicted schematically in Figs. 1 and 2. The cleaning system 100 is shown located on a building 104 having a number of window panels 106 that are divided by mullions 108, including both vertical and horizontal dividers. The cleaning system includes a vehicle 110 that is suspended below a positioning system 120 by one or more tethers 124. The positioning system 120 is secured and anchored at the top of the building 104 such that the cleaning vehicle 110 is disposed adjacent the outside vertical surface 132 of a building (Fig. 2) . The positioning system 120 is able to position the vehicle 110 at desired locations on the building surface under control signals provided from the vehicle 110 to the positioning system 120. The positioning system includes a lateral movement system for providing lateral movement of the vehicle via the at least one tether, and a lifting arrangement for providing vertical movement of the vehicle via the at least one tether. Communications lines 112 are provided between the vehicle 110 and positioning system 120 for providing the control signals and returning feedback and sensor signals.

[0035] Water 122 and power supply 126 is provided at the rooftop and supplied to the vehicle 110 by supply lines 128, 130.

[0036] An embodiment of the vehicle will now be described with reference to Figs. 3 to 7. The vehicle 110 includes a main plate 200 that provides support to the components of the cleaning vehicle. The main plate 200 may be a composite, CNC machined ply and aluminium sandwich base plate. This structure is used to reduce weight and increase rigidity. The sandwich is constructed using adhesive with pressure applied during curing to ensure a strong and even bond. Aluminium channel, angle and section are used together with rivets to create a light and strong superstructure. The plate 200 may have a trim 202 for protecting the lamination. The plate 200 may have other forms of construction, including a lightweight metal plate. The main plate 200 may have an upper edge 204, lower edge 206 and left 208 and right 210 edges.

[0037] The base plate has a front face 212 that, in use, faces toward the building and a back surface 214 which, in use, faces outward of the building.

[0038] These terms of orientation are provided for ease of description and intend to refer to the deployed configuration of the cleaning vehicle, e.g. disposed vertically on the side of a building. These terms of orientation are not intended to be limiting in any manner. Further, the front and back labels are relatively arbitrary and thus the outward face 214 could be considered to be the front of the vehicle.

[0039] The main plate 200 supports a frame that extends outward from the back surface 214 of the plate 200 for supporting an arrangement of propellers and associated motors. The frame may be lightweight aluminium rectangular tube and may include a left arm 222, right arm 224 and a horizontal cross piece 226 joining the outward ends of the left and right arms. Similarly, the frame may include a top arm 228, bottom arm 230 and vertical cross piece 232.

[0040] Extending upward of the left and right arms 222, 224 are hang arms 236, 238. The hang arms 236, 238 have a tether point 240, 242 at their ends that provides an attachment for the tether to the positioning system 120. The hang arms may be located along the side arms 222, 224 at a location to provide substantially vertical balance of the cleaning vehicle when tethered . [ 0041 ] Left and right propeller support arms 250, 252 extend vertically across the horizontal cross piece 226 and provide a mount for multiple propellers and their motors.

[ 0042 ] In one embodiment, an eight propeller arrangement is provided. Two push off propellers 260, 262 are mounted at the top and on the outside of the propeller arms 250, 252 and are arranged to generate thrust in a manner to propel or push the vehicle away from the building. That is, the propellers are mounted for operation in a vertical plane, i.e. with a horizontal axis of rotation. An additional two push off propellers 264, 266 are mounted at the bottom and on the outside of the propeller arms.

[ 0043 ] Two push on propellers 270, 272 are mounted on the top and on the inside of the propeller arms and are arranged to generate thrust toward the building. Two additional push on propellers 274, 276 are mounted at the bottom and on the inside of the propeller arms 250, 252. While eight propellers are shown, a different number of configuration of propellers may be provided depending on various factors including the size and weight of the vehicle 110, the requirement to carry other servicing components, required speed, etc.

[ 0044 ] In one embodiment, the propellers may be Phantom 3 propellers and accompanying motors, made by Da-Jiang Innovations (DJI) of China. The propellers may have approximately 23cm diameter blades. The person skilled in the art will readily understand that a variety of propellers are commercially available and that many such propellers will be suitable for the present application. In particular, while a certain sized unit is described herein for illustrative purposes, the person skilled in the art will readily understand that the unit may be scaled for larger applications. [ 0045 ] The propeller motors may be air cooled to facilitate long constant run time.

[ 0046 ] At least some of the propellers may be mounted in a rotatable mount, such as a cradle 280 that allows the propeller to be rotated about a vertical axle or pin to change the direction in which the propeller generates its thrust. The rotation of the cradle 280 may be controlled by a servo motor mounted within a servo housing 286. The cradle allows the angle of thrust to be varied to compensate for crosswinds, as will be described in more detail below.

[ 0047 ] On the inside surface 212 of the plate 200, there are mounted the cleaning components of the cleaning vehicle. In one embodiment, the cleaning components include motorized rotating cleaning disks 310 fitted with removable cleaning pads. The cleaning pads are preferably washable and reusable. In the embodiment depicted, three cleaning pads are mounted in a triangular configuration. Other arrangements of the cleaning pads will be apparent to the person skilled in the art and may depend on various factors, including the size of the cleaning vehicle, weight requirements, etc. The cleaning pads overlap laterally to ensure good cleaning coverage in a vertical cleaning strip as the cleaning disks scrub the building surface removing dirt.

[ 0048 ] The cleaning disks are driven by a motor and pulley arrangement. Fig. 5 shows the back face 214 of the cleaning device 110 with the propeller framework removed. Each cleaning disk 310 is mounted for rotation on a cleaning disk axle 312 that passes through the plate 200. Mounted on the back surface of each axle 312 is a pulley wheel 314. A motor 316 and gearbox 317, such as a planetary gearbox is mounted in alignment with the axle 319 of one of the cleaning disks and this pulley may be considered the drive pulley 320. In the embodiment depicted, the drive pulley 320 is the middle of the three cleaning disks 310, as this supports balance of the vehicle, though any disk may be selected subject to design and placement constraints. The motor 316 and gearbox 317 may be supported on a support 322 that is in turn supported by the lower frame member 230. The motor 316 may include a waterproof housing.

[ 0049 ] The slave pulleys 314 may be coupled to the drive pulley 320 by a belt, cord or similar, such as Polycord (not shown) . The motor 316 operates to turn the drive pulley 320 which in turn drives the slave pulleys 314, thereby causing all three cleaning disks 310 to turn.

[ 0050 ] The cleaning components may also include one or more misting nozzles 382 for efficiently spraying the building surface with water to assist in the removal of dirt by the cleaning disks. The misting nozzles may be supplied with water via a water distribution line. A line of misting nozzles may be disposed above the cleaning disks. One or more electronically operated valves may be disposed in the water distribution line for controlling the water flow.

[ 0051 ] The cleaning components also include one or more wiper blades 380 or squeegees disposed generally horizontally above the cleaning pads, and above the misting nozzles 382. The wiper blades are typically the trailing component of the cleaning vehicle and thus the last component to contact the building surface. The wiper blades act to wipe and dry the building surface.

[ 0052 ] To assist in controlling the placement of the vehicle on the building surface, a set of contact wheels 340 are located on inwardly extending arms 342 (Fig. 3) . In one embodiment, the wheels are omni wheels that freewheel in the vertical direction but are driven in the horizontal direction. The wheels 340 are mounted on axles 344 that are driven by pulleys 346. A belt drive system may be provided for horizontally driving the omni wheels. Fig. 6 shows the front view of Fig. 5 with the cleaning disks 310 removed. As shown in Fig. 6, a second motor 348 and gearbox 350 may be secured by its housing to the plate 200 via one or more mounting brackets 352. The gearbox 350 may be provided with a vertical drive axle that turns a drive pulley 356. A pulley belt (not shown) couples the drive pulley 356 with a pulley 358 on a vertical axle 360. A series of pulleys 362 are disposed along the axle 360 and are coupled via belts or cords 362 to the wheel pulleys 346.

[ 0053 ] The vehicle 110 uses an array of ultrasonic sensors disposed across the vehicle that provide location information. Sensors can look towards the building to determine the distance of the vehicle from the building. Sensors can also look left, right, up and down and provide feedback as to the vehicle's proximity to obstructions such as mullions. Left side sensor 410 and top side sensor 412 are shown. The person skilled in the art will understand that proximity sensors can be deployed virtually anyway on the vehicle for detecting proximity of the vehicle to surrounding objects. In one embodiment, the proximity sensors may be HC-SR04 Ultrasonic Sensors, though other forms of sensor may be used. In an alternative embodiment, one or more optical sensors may be deployed as well as or in place of the ultrasonic sensors. Optical sensors may sense colour changes and be used to detect transitions, e.g. at a joint between panes of glass.

[ 0054 ] The vehicle 110 includes at least one anemometer 416 that provides signals indicative of crosswinds that can be used to stabiles the vehicle during cleaning cycles and assist in positioning during movement cycles . The anemometer may be located to sample crosswinds without affect from propeller fans.

[ 0055 ] The vehicle 110 may include one or more position sensors. The one or more position sensors may include one or more accelerometers , one or more gyroscopes and one or more GPS modules. Positional data, including velocity data, from the position sensors may be provided to the processor.

[ 0056 ] The propeller arrangement is required for providing separation between the cleaning vehicle and the building surface to allow the vehicle to traverse mullions and other building obstructions. The actual positioning of the vehicle, i.e. height and lateral positioning, is provided by positioning system 120. A prototype of the positioning system is shown in Figs. 8-10. The positioning system 120 includes a track 510 that may be distributed across the edge of the building at the rooftop. The track 510 may be a permanent fixture of the building or may be installed as part of the cleaning service.

[ 0057 ] The track 510 provides a guide to a motorized slider 520. The slider 520 is shown in more detail in Fig. 9. The slider 520 moves along the track under the control of a stepper motor 522 and gearbox 524. The use of a stepper motor 522 allows relative precise location of the slider along the track to be known. Various drive mechanisms may be employed. In one embodiment, the drive mechanism may include a toothed belt and cog system in which cogs 528 turning under control of the stepper motor 522 move the cogs, and with it the slider, along a tooted belt 526 that is fixed within the slider track 510. In alternative embodiments, a rack and pinion system, or a worm drive, may be utilized.

[ 0058 ] Connected to the slider is a tethering system (Figs. 9 and 10) . In one embodiment, the tethering system includes a horizontal bar 530, disposed at each end of which is a pulley 532, 534. A tethering cord 536 extends from a winding or winch bar 538 to each tether anchor 240, 242 of the cleaning vehicle 110 via the pulley 532, 534. The winch mechanism 538 is rotated by a winch motor 540 and gearbox 542 to release or retract the tether 536, thereby lowering or raising the cleaning vehicle 110. In one embodiment, the winch utilizes a worm drive gearbox with an antiback-drive nature meaning that a separate braking system is not required to hold the weight of the cleaning vehicle at a given height. In addition, the smooth operation allows for minimal vibration which otherwise may cause a disturbance to the building occupants.

[ 0059 ] The pulleys 532, 534 provide a tether redirection mechanism between the winch and the tether anchors 240, 242 that increases the stability of the suspended cleaning vehicle. In one embodiment, the length of the tethering bar 530, i.e. the distance between the pulleys 532, 534 is wider than the separation of the tether anchor points 240, 242 at the cleaning device 110. This produces a generally trapezoidal configuration of the tethering line that acts to reduce swinging and twisting of the suspended cleaning vehicle 110. In one particular embodiment, the length of the tethering bar is approximately 1000mm, though this may be scaled accordingly. Pulleys 532, 534 have advantage as the redirection mechanism as they provide a low friction, low wear redirection of the tether. However, other redirection mechanisms, such as eyelets or rings at the ends of the tether bar could also be used.

[ 0060 ] By the slider stepper motor and the winch, lateral position and height of the cleaning vehicle can be controlled. Controls for the stepper motor and winch can be generated in the electronics of the cleaning vehicle and relayed to the positioning system via communications cable, serial line or by wireless means such as Bluetooth, Near Field Communications or WiFi .

[ 0061 ] The cleaning vehicle 110 includes on board control systems that supply power and control signals to the vehicle components described above. Because the main sensors and feedback mechanisms are on board the cleaning vehicle, it has been found that incorporating the main electronic intelligence into the cleaning vehicle 110 is preferred to having the intelligence in the positioning system 120 and relaying the sensor and control signals to and from the positioning system. The electronics of the system are represented schematically in Fig. 10. In one embodiment, the on-board electronics 700 includes one or more processors 710. In one particular embodiment, one or more Arduino processors may be used. Arduino processors include PWM ports for providing PWM signals to the propeller motors. The on board processors 710 include operatively associated memory 712 that can store executable code and programs for operating the cleaning vehicle. The memory 712 may also store data, such as building data as will be described in more detail below. The memory 712 may also include random access memory or similar used during execution of the program code. The processor 710 executes the control programs during which, the processor may receive feedback signals from an array 716 of sensors 718 and distribute power and control signals to the various components, such as the propellers 720, cleaning disk motors 722 and wheel drive motor 724. The sensors 718 may include the on-board sensors including, without limitation, proximity sensors, anemometer, propeller feedback systems, tilt servos, motors, temperature sensors, water pressure sensors, accelerometers, gyroscopes, GPS units, etc. The processor 710 may also receive off-vehicle feedback, such as from the positioning system components 732 stepper motor, winch drive, etc .

[ 0062 ] The onboard electronics include one or more power supplies 726 that receive supplied power 728, e.g. mains power supplied from a cable connected at the rooftop, convert the power to the required voltage and distribute the power to the relevant component. In one embodiment, the power supplies 726 include an 18V power supply for powering the propeller motors. The power supplies may also include one or more 12V supplies for distributing power to the other components, such as the cleaning disk motors, water pumps, water supply control valves. The sensors and other components may receive power stepped down to the required voltage for that component. The power supplies 726 may include battery storage, such as one or more Lithium Polymer (LiPo) batteries that can provide stable power to the on-board components in the event of a power interrupt.

[ 0063 ] The on-board electronics may be connected to the positioning system 732 and provide control signals to the stepper motor and winch drive. Power to the positioning system can be provided directly from a rooftop mains supply without needing to first travel to the cleaning vehicle. This minimizes the distance that power is transferred and the cabling required.

[ 0064 ] The electronics 700 may include a communications module 730 that provides a communications interface between the processor 710 and the positioning system. The communications module 730 may adopt any suitable communications method including wired, e.g. serial, USB, ethernet, or unwired, e.g. Bluetooth, NFC, WiFi or mobile telephone protocols for communication with the positioning system. In addition, the communications module 730 may allow for communications with peripheral devices, such as a computer terminal. The electronics 700 may transmit operational and status signals to a monitoring terminal and may receive control programs, software updates, emergency stop signals etc. from the computer terminal via the communications module 730.

[ 0065 ] Pulse Width Modulation (PWM) motor controllers are used to control the speed of each motor. These devices work by interpreting a low voltage, low current PWM signal input and using this input to adjust the higher voltage, high current output to the motor itself.

[ 0066 ] The propeller motors can consume substantial power. The electrical supply cable from the rooftop to the cleaning vehicle is therefore a high current cable. The requirement for high current from a roof top mains supply to the vehicle can provide a constraint on the building height at which the vehicle can operate. Beyond a certain height, current losses through the cable may become too substantial to be practical. To remove this constraint, power may be supplied at higher voltages with lower current, and then stepped down at the vehicle through a trans former .

[ 0067 ] Having described the general configuration of components in particular embodiments, operation of the cleaning system will now be described.

[ 0068 ] In one embodiment, a general method of operation follows the flowchart 800 of Fig. 11. At step 802, the cleaning vehicle is controlled to land on and engage a target building panel. The initial engagement may be autonomous, semi- autonomous, or manually controlled. At step 804, the cleaning vehicle executes a movement routine to locate at least one edge of the panel. In one embodiment, the movement routine maneuvers the cleaning vehicle to a corner of the panel. The movement routine may execute by providing movement signals to the slider and/or winch of the positioning system while utilizing feedback from the proximity sensors. The edge of the panel may be detected by the proximity sensors. At step 806, the cleaning vehicle executes a cleaning routine. In one embodiment, the cleaning routine may include an alternating series of cleaning phases and repositioning phases. For example, in a cleaning phase, the cleaning vehicle may move vertically downward by sending control signals to the winch, while simultaneously activating the cleaning components of the vehicle including the cleaning disks and water supply. Optionally, the push-on propellers may also be activated to increase the pressure of the cleaning vehicle against the panel . The cleaning phase may continue until the proximity sensors detects the bottom of the panel. If the panel is not complete (determination step 810), i.e. the proximity sensors have not detected the opposite side edge, then a repositioning phase occurs 812. In a repositioning phase, the cleaning components are deactivated and the cleaning vehicle may move a cleaning width sideways, allowing for some cleaning overlap, and to the top of the panel. The next cleaning phase down the next vertical cleaning strip may then commence. Some or all of the repositioning phase may occur with the cleaning vehicle in contact with the panel. For example, the wheels 340 may be driven in tandem with the slider while activating the push-on propellers. This sequence minimizes the amount that the cleaning vehicle will swing on its tether and provides for a more precise repositioning of the cleaning vehicle for the next cleaning phase. Alternatively, by activating the push-off propellers, some or all of the repositioning phase may occur with a separation between the cleaning vehicle and the panel. This ensures minimal contact between the vehicle and the cleaned portions of the panel.

[0069] The alternating sequence 806 of cleaning and repositioning steps occurs until the cleaning vehicle determines that the panel is complete (step 810) . For example, the cleaning vehicle may determine from the proximity sensors that it has encountered the corner diagonally opposite to the starting corner. If there are more panels to be cleaned (determination step 814), the cleaning vehicle executes a jump routine (step 816) to clear the current panel and land on the next target panel. The process returns to step 802 for the next target panel. Otherwise, if all panels in the cleaning program are cleaned, which may be determined by programming and/or by feedback from the sensors, positioning system, etc. the cleaning vehicle may execute a shutdown procedure 818. For example, the cleaning vehicle may return to a starting position by retracting the winch to raise the cleaning vehicle to the roof. Alarms may also be sent to a remote monitoring system to indicate to an operator that the building cleaning cycle is complete.

[0070] A particular cleaning routine will be described with reference to Fig. 12 which shows the cleaning vehicle 110 having landed on a portion of a building surface having a number of window panels, including an initial target window panel 910. The window panel 910 is bordered on each of the top, bottom, left and right edges by a mullion 912 or similar divider that separates the current panel from adjacent panels 920, 922. The mullions have a depth, i.e. project outward of the building and therefore prevent the vehicle from rolling or sliding over the mullion .

[0071] The cleaning vehicle 110 executes a control program that provides control signals to the positioning system and the onboard propellers to maneuver the cleaning vehicle to engage with a target panel. The initial panel may be targeted with the assistance of a human operator. Alternatively, the cleaning vehicle may be programmed with its starting position relative to an initial target window, after which the cleaning vehicle can execute its control programs to maneuver to the initial target window. An initial movement to locate the initial target panel may involve moving the slider a distance sideways from the starting position and operating the winch to lower the vehicle a vertical distance from the starting position to the initial target panel while simultaneously operating the push off propellers to ensure that the cleaning vehicle is not encumbered by the building structure, mullions etc. in its path to the initial target panel.

[0072] The landing procedure may target the approximate middle of the target panel to ensure that the vehicle lands somewhere in the correct target panel without inadvertently encountering the mullions, however it is not imperative that the middle of the panel be found. Once the positioning system, has been used to maneuver the cleaning vehicle in alignment with the target panel, the push off propellers can be deactivated, and, optionally, the push on propellers can be activated to urge the cleaning vehicle 110 into contact with the target panel 910. Depth proximity sensors may be used to control the rate at which the cleaning vehicle approaches the target window 910.

[0073] Once contact is made with the window, the cleaning vehicle 110 may execute a cleaning routine. The cleaning vehicle may be programmed to clean the window according to a particular routine. In one embodiment, the cleaning routine may be to clean top to bottom, left to right. This pattern is advantageous because it allows the cleaning vehicle to rely on proximity sensors rather than having to accurately track the vehicle's position to ensure full cleaning coverage. However, other patterns may be apparent to the person skilled in the art. Thus having landed on the window panel, the cleaning vehicle may activate a movement cycle by sending control signals to the positioning system to operate the slider to move the cleaning vehicle left and to operate the winch to raise the vehicle, following a path as denoted by arrow 952. This movement may be conducted with the vehicle 110 in contact with the window, as denoted by the solid line arrow 952. As the cleaning vehicle moves, the left and upper proximity sensors will detect the presence of the left and upper mullions respectively and stop the vehicle when the top left corner of the window is encountered .

[ 0074 ] Having located the top left corner of the window, a cleaning cycle may be activated. The on-board processor may send control signals to start the rotation of the cleaning disks and to the water flow valves to begin spraying water through the mist nozzles. Optionally, the push on propellers may be operated to ensure that the cleaning vehicle applies pressure to the window. The winch drive is then operated to lower the cleaning vehicle down the window, following path 954 until the lower proximity sensor detects the lower mullion. The cleaning cycle may be deactivated by closing the water flow valve and deactivating the cleaning disks. The push on propellers may be turned off and the push off propellers may be operated at low power sufficient to provide a degree of clearance between the cleaning vehicle and the window. The slider is then operated to move the cleaning vehicle one cleaning width, e.g. combined width of the wiper blades and/or cleaning disk, to the right. The winch is simultaneously operated to drive the cleaning vehicle back up to the top mullion. The combination of these positioning signals results in path 956 being followed, without contact between the vehicle and the window, as indicated by the path 956 being shown in broken line. At this point, the cleaning cycle may recommence and the vehicle will follow the next vertical cleaning path 958. The process of cleaning and movement cycles may alternate until the proximity sensors detect that the cleaning device has reached the right mullion and cleaned the right most strip of the window, indicated by path 960. The cleaning device thus finishes cleaning of the window panel at the bottom right corner 962 of the window panel 910. In the general case, the final cleaning strip 960 may be not be a full width because the cleaning vehicle will contact the right side mullion or border without travelling a full cleaning width sideways. However, to ensure a thorough cleaning, the final strip should be performed and thus there may be an increased overlap with the immediately preceding cleaning strip. This is represented in Fig. 12 by the spacing between the cleaning path 960 and the immediately preceding cleaning path being closer than the spacings between the other cleaning paths.

[0075] To assist in guidance, the control processor may track the movements of the cleaning vehicle to determine the height of the window panel. This may enable the cleaning device to return to the top of the window faster, without losing precision and without risk of contacting the mullion too hard.

[0076] Having completed cleaning of one window, the cleaning device initiates a jump cycle to clear the mullion and land on the next window. The next window panel may be determined on the fly. For example, the cleaning device may clean windows of a first row left to right. At the end of the row, the cleaning device may move to the next lower row and clean the windows of that row right to left. In doing so, the cleaning vehicle may use the same top to bottom, left to right cleaning pattern on the panels of the lower row, or may reverse the process to clean top to bottom, right to left. The end of a row may be determined by the limit of the slider in the track or by a determined number of steps of the stepper motor.

[0077] The jump procedure may be initiated by powering the push off propellers to propel the cleaning device away from the window by a distance sufficient to clear the mullion with a reasonable safety factor. In one embodiment, the distance may be determined by programming of a mullion height into a cleaning algorithm for the building. Alternatively or in addition, the distance may be determined using inward directed proximity sensors (depth sensors) that detect the separation distance between the cleaning vehicle and the building. The sideways looking proximity sensors may also be used to detect when the cleaning device has pushed off sufficient to clear the depth of the mullion.

[0078] Once the cleaning device has pushed back sufficiently the cleaning device controls the positioning system to position the cleaning device within the borders of the next window, following jump path 964. To ensure that the cleaning device clears the mullion before pushing back toward the window, the cleaning device can target the approximate middle of the next window. For example, to target the window to the right from the bottom right corner of the cleaned window, the cleaning device can move approximately half a window width to the right and raise half a window height. Once the cleaning device lands on the target window, the positioning system can again locate the top left corner of the window ready to recommence the cleaning cycle.

[0079] During jump maneuvers, the cleaning vehicle may be subject to the wind environment around the building, including crosswinds. The anemometer is able to measure the wind speed and direction. The wind parameters are supplied to the processor and used to modify the control signals for positioning the cleaning vehicle. For example, a particular jump maneuver may require the push off propellers to operate at 70% power under no wind conditions. If the wind is blowing the cleaning device into the building, then 100% power to the propellers may be required to provide sufficient clearance from the building. If there is a cross wind, the processor may determine that the jump maneuver will require 90% power with a 10 degree rotation of the push-off propellers in their respective tilt cradles to counteract the crosswind and maintain the cleaning vehicle 110 vertically below the slider. During the jump maneuver, the anemometer is able to provide constant feedback to the processer and the processor may be programmed to dynamically adjust the operating parameters of the propellers to provide smooth transitions.

[ 0080 ] Experimentation may determine various routines and programs, power requirements, tilt adjustments, etc. to make wind-based adjustments on the fly.

[ 0081 ] Because the cleaning vehicle is always tethered to the positioning system, the cleaning vehicle may be considered to be a pendulum capable of swinging both laterally, i.e. across the face of the building, and outward of the building. Considering the outward pendulum component, at short pendulum distances, i.e. near to the rooftop positioning system, the thrust required to gain clearance of the mullion may be substantial. As the cleaning vehicle moves down the panels of the building, the pendulum length will increase and the pendulum angle at a certain clearance will decrease, and therefore the thrust required to gain the same amount of clearance will reduce. The control programs may therefore take account of the current height relative to the positioning system when calculating the propeller power, in particular for the push off propellers .

[ 0082 ] Sideways positioning of the cleaning vehicle is controlled by the slider mechanism of the positioning system. When the slider moves laterally, there will be a lag in the cleaning vehicle movement due to the tether. Likewise, when the slider stops, the cleaning vehicle will have momentum on the tether and will continue to swing, operating on a sideways pendulum. The sideways pendulum effects may be reduced using the trapezoidal tether arrangement described previously. However, there can still be substantial time taken for the cleaning vehicle to come to equilibrium, in particular at longer pendulum lengths. The pendulum effects can also affect the precision of the positioning movements. To minimize the lateral pendulum effect, the control processers may provide pendulum counteracting signals to the motors of the cleaning vehicle. Thus, whenever, the cleaning vehicle sends a signal to the positioning system to move sideways, a corresponding signal is sent to the lateral drive systems of the cleaning vehicle to actively drive the lateral movement of the vehicle rather than the vehicle being passive to movement of the slider. If the vehicle is in contact with the window while moving sideways, the movement may be controlled by a combination of the push-on propellers and the omni wheels. That is, the omni wheels may be driven at the same rate as the slider so that the cleaning vehicle remains vertically below the slider. As the slider comes to a stop, the cleaning vehicle can be slowed so that it does not overshoot its final intended position. Any of the propellers may also be tilted to produce lateral thrust to assist in the lateral movement and lateral braking.

[ 0083 ] Similarly, if the lateral movement of the cleaning vehicle is undertaken without contact with the window, lateral drive comes from tilting the propellers and thus the propellers can be tilted to drive the cleaning vehicle laterally. Opposing propellers may be activated as the cleaning vehicle approaches its intended position to prevent overshoot.

[ 0084 ] The use of a stepper motor and a suitable encoder for the winch worm drive in the positioning system allows the coordinates of the cleaning vehicle to be known at all times, relative to its starting position, with sufficient precision to enable the system to know which window the vehicle is currently engaged or aligned with. In one embodiment, a building map may be uploaded into a memory of the cleaning vehicle. The building map may describe information pertaining to aspects of the building panels to be cleaned. For example, the building map may specify the number of windows on a particular side of the building, the arrangement of the windows such as the number of rows and number of windows per row, an approximate size of each panel, the width of separating mullions, the depth of the mullions, whether the windows are regular across the building, and a starting window to be used as the initial landing of the cleaning vehicle. The building map may also specify an order for cleaning of the windows .

[ 0085 ] The control program executing in the vehicle processors may reference the building map to calculate jump maneuvers from one window panel to the next. With reference to Fig. 12, the building map may specify an approximate configuration of windows and a window sequence, as denoted by the sequence number in the top left corner of each panel. The panel sequence may be optimized to minimize the distance of the jump maneuvers, indicated by the dashed lines 966. While this may take some initial setup, the building map can be used repeatedly on successive cleanings. If the cleaning system is dedicated to the building, the cleaning vehicle may permanently store the building map. Alternatively, the building map may be uploaded to the cleaning vehicle each time the vehicle is used to service that building.

[ 0086 ] When a jump maneuver is to be undertaken, the vehicle processor references the building map to determine the location of the approximate center of the next panel in the sequence and plots a move sequence from its current position to the target location. The processor then sends movement signals to the positioning system and propellers to undertake the move sequence .

[ 0087 ] While specific embodiments and examples make reference to cleaning of building windows, the person skilled in the art will recognize that windows are just one form of building panel and that other building panels may be cleaned using the cleaning system as herein described.

[ 0088 ] In the embodiments presently described, the positioning system utilizes a track secured at the rooftop on the building edge. There are various factors that may limit the building height on which the cleaning system may be deployed. These include the length of power cables, communications lines, water lines and the increased risk and instability that comes with increasing pendulum length. To overcome some of these issues, in an alternative embodiment, the positioning system may be secured on a mobile maintenance gantry. While these systems can be cumbersome to deploy, the gantry does not need to access each window. Instead, the gantry can be lowered to a position that allows the cleaning system to be deployed to a range of windows while the gantry remains fixed. Thus, movement of the gantry is minimized while providing full cleaning service to the building windows.

[ 0089 ] The cleaning system as herein described can provide compensation for crosswinds. However, there is a limit to the conditions in which the propellers of the cleaning vehicle can stabilize the vehicle. If the wind conditions become excessive the control routines may operate to retract the vehicle to the rooftop to park the vehicle. Alternatively or in addition, the control routines may operate the push-on propellers at full power to force the cleaning vehicle against the building as hard as possible, with thrust to counteract any crosswinds if required. A problem with operating the cleaning vehicle in this manner is that it consumes a significant amount of power and may lead to propeller motor burnout and will not be viable during a power interrupt.

[ 0090 ] In one embodiment, the cleaning vehicle may be fitted with an emergency device that enables the cleaning vehicle to latch on to the window and maintain position at low or zero power. In one embodiment, the safety device may include one or more solenoid operated suction cups. To engage the safety device, the controller, having detected an unsafe operating environment, e.g. due to excessive winds, may operate the propeller motors to drive the cleaning vehicle hard against the window. The solenoids may then be operated so that the suction cups engage and adhere to the window panel. The solenoids may be failsafe so that if power to the solenoid is cut, the suction cups remain secured to the window. This form of safety mechanism allows the cleaning vehicle to park in a low power mode on the building until the winds reduce to a safe operating level. While a solenoid operated suction cup is one possible latch mechanism, other latch mechanisms will be apparent to the person skilled in the art.

[0091] The use of the safety mechanism allows the cleaning device to autonomously handle unsafe operating environments as they arise.

[0092] The present embodiments have the ability to clean building facades in an autonomous or semi-autonomous manner, even where the building has complicated mullion structures. Advantageously, the cleaning system can clean with minimal water and minimal cleaning agents, which preserves window coatings and minimizes environmental impacts.

[0093] The term semi-autonomous as used herein describes that some human involvement may be required to set-up, control, operate or monitor the system even after the initial set-up. However, even under semi-autonomous control, the requirement to have a human presence at the cleaning interface, i.e. working at height on the outside of the building is removed, thereby providing enhanced safety benefits. [ 0094 ] While the present embodiments relate to cleaning of building surfaces, in alternative embodiments, the cleaning vehicle may be deployed for other purposes. For example, the cleaning components may be replaced, or supplemented, with other components for engaging with the vertical surfaces of a building. In one specific alternative, one or more cameras may be disposed on the vehicle and used to inspect the building surfaces. In a further alternative, the vehicle may be used for maintenance of plants etc. on a greenwall. In a further alternative, the vehicle may be fitted with one or more painting components for painting one or more panels of the building.

[ 0095 ] Although embodiments of the present invention have been illustrated in the accompanied drawings and described in the foregoing description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit of the invention as set forth and defined by the following claims.