GB2344900A

GB2344900A - Robotic floor cleaning device with obstacle detection

Info

Publication number: GB2344900A
Application number: GB9827777A
Authority: GB
Inventors: David Lindsey Bisset; Michael David Aldred
Original assignee: Notetry Ltd
Current assignee: Dyson Technology Ltd
Priority date: 1998-12-18
Filing date: 1998-12-18
Publication date: 2000-06-21
Also published as: WO2000038025A1; GB9827777D0; GB0113417D0; AU1575300A; GB2361553B; GB2361553A

Abstract

A robotic floor cleaning device is programmed so that it firstly completes a circuitous path (A, B, C...I) around the edge of a room to be cleaned. Alternatively, the cleaning device completes a path around a feature of the room or an object in the room. The cleaning device avoids any obstacles in its path using various sensors such as ultrasonic or infra-red transmitters and receivers. Once the circuitous path has been completed (at I), the cleaning device then moves outwardly or inwardly by the width of the device, and completes a second path (I, J, K...T). The cleaning device then continues to move outwards or inwards by its own width after each subsequent path, so as to travel in a generally inwardly or outwardly spiral manner until the floor of the room, apart from areas occupied by obstacles, has been cleaned. The cleaning device recognises when each circuitous path has been completed by storing information relating to the ambient light level, or information from the ultrasound sensors, each time the device changes direction, and comparing it with previously stored information.

Description

IMPROVEMENTS IN OR RELATING TO FLOOR CLEANING DEVICES This invention relates to a method of operating a floor cleaning device, more particularly a robotic floor cleaning device and typically a robotic vacuum cleaner, and to a floor cleaning device programmed to operate in a particular way.

It is known to provide vacuum cleaners which are fed a detailed map of a room and which are then trained to reciprocate to and fro from one side or one end of a room to the other side or other end of the room. It is also known to provide a robotic vacuum cleaner which is lead around a room in a training cycle and which will then repeat the cycle from information stored in memory. A robotic vacuum cleaner has also been proposed which travels round the edge of a room and then moves about the room in random fashion bouncing off obstacles as it moves around.

According to a first aspect of the present invention there is provided a method of operating a robotic floor cleaning device so that the floor cleaning device (a) firstly completes a traverse around the edge of a room (or around a feature of the room or an object in the room) avoiding any obstacles in its path, and (b) then moves inwards (or outwards) by, or substantially by, the width of the cleaning device and completes a second traverse, the cleaning device continuing to move inwards (or outwards) by, or substantially by, the width of the cleaning device after each traverse so as to travel in a generally inwardly (or outwardly) spiral manner until the floor of the room, apart from areas occupied by obstacles, has been cleaned.

Preferred and/or optional features of the first aspect of the invention are set forth in claims 2 to 5, inclusive.

According to a second aspect of the invention there is provided a robetic floor cleaning device comprising power operated means for moving the cleaning device along the floor and a navigation system for identifying the location of the cleaning device in a room and for navigating the cleaning device around the room, the cleaning device being programmed so that it firstly completes a traverse around the edge of a room (or around a feature of the room or an object in the room) avoiding any obstacles in its path and then after each completed traverse moves inwards (or outwards) by, or substantially by, the width of the cleaning device until the floor of the room, apart from areas occupied by obstacles, has been cleaned.

Preferred and/or optional features of the second aspect of the invention are set forth in claims 8 to 13, respectively.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of one embodiment of a robotic cleaning device according to the second aspect of the invention, Figure 2 is a circuit diagram of a power management system and a navigation system for the robotic cleaning device shown in Figure 1, and Figure 3 is a schematic view illustrating one embodiment of a method of operating the robotic cleaning device according to the first aspect of the invention.

Referring firstly to Figure 1 of the drawings, there is shown therein a robotic floor cleaning device in the form of a robotic vacuum cleaner comprising a main body 10, two drive wheels 11 (only one of which is shown), a brushbar housing 12, two rechargeable batteries 13 and 14, a dual cyclone 15 of the type described in EP-A0042723, a user interface 16, a light detector 17 and various sensors 27 to 31 which will be more particularly described hereinafter. The light detector 17 detects light received from a plurality of compass points around the vacuum cleaner and is more particularly described in our co-pending British Patent Application No. [our reference GBP0099] of even date.

The circuit shown in Figure 2 comprises the two rechargeable batteries 13 and 14, a battery and motor management system 18, a motor 19 for driving a suction fan, motors 20 and 21 for driving the left and right hand wheels 11 of the vacuum cleaner, a motor 22 for driving a brushbar of the vacuum cleaner, processing circuitry 23 (which includes a microprocessor and field programmable gate arrays), left and right hand sensor interfaces 24 and 25, respectively, a user interface board 26 and the light detector 17.

The robotic vacuum cleaner is also equipped with a plurality of infra-red transmitters 27a and infra-red receivers 27b, a plurality of ultrasonic transmitters 28 and ultrasonic receivers 29, threshold detectors 30 for detecting the presence of a portable threshold locator placed, for example, at the entrance to a room or at the edge of a staircase and one or more pyroelectric detectors 31 for detecting animals and fires.

There are four main ultrasonic receivers 29 svhich face forwards, rearwards and to opposite sides of the robotic vacuum cleaner. The signals received by these receivers not only provide information representative of distance from a feature of the room or from an object in the room but the amplitude and width of the received signals vary according to the sensed size, shape and type of material of the object.

Figure 3 illustrates a method of operating the robotic vacuum cleaner. The cleaner is, typically, placed alongside a wall and energised to move forwardly along the edge of the room. The various sensors 27 to 31 will detect obstacles in the room and other room features, such as comers of a room and fireplaces, and the processing circuitry 23 will navigate the robotic vacuum cleaner in order to avoid any such obstacles and to change direction when a feature of a room is reached. At each change of direction caused by reaching a feature of the room, the processing circuitry 23 will store information received from the light detector 17 and also from the four main ultrasonic receivers 29. It will also store information on the direction in which the cleaner turns at each change of direction. It will also periodically monitor the information received from the detector 17 and the four main receivers 29 and compare this with information previously stored. When the robotic vacuum cleaner reaches a position in which the information received from the light detector 17 and the four main receivers 29 is the same or substantially the same as information previously stored, the processing circuitry 23 will determine that the robotic vacuum cleaner has completed a complete traverse around the room and is programmed to cause the robotic vacuum cleaner to step inwards by one cleaner width. The processing circuitry 23 will then be able to identify further changes of direction by comparing the information received from the li, detector 17 and the four main receivers 29 with previously stored information and this will enable the robotic vacuum cleaner to navigate itself around the room avoiding any obstacles in its path in a generally inwardly spiral manner.

More specifically, if the vacuum cleaner starts from Position A shown in Figure 3 and moves along the edge of the room in a clockwise direction, at Position B it will sense the presence of the wall in front of it and will turn 90 to the right. It will already know from the sensors that there is a wall on its left hand side. The cleaner will then continue until it reaches Position C when it will sense the presence of the table and will turn so as to run along the side of the table. The cleaner is programmed to keep one side close to the nearest wall or obstacle or close to the most recently covered circuit of the room. Thus, when it reaches Position D it will turn to the left and move forwards along the front of the table until it reaches Position E when it will turn again to the left until it reaches Position F. At Position F, it will sense the presence of the wall in front of it and will turn to the right and proceed along the wall until it reaches Position G. It will then tum right and pass through Position H until it reaches Position I. At Position I, the light detector and four main receivers 29 will detect information which is the same or substantially the same as they detected at Position B. At this point, the cleaner will move inwards by or substantially by one cleaner width and will then continue to follow the initial traverse around the room (but one cleaner width within that initial traverse) until it senses the existence of the sofa at Position O. It will then run along the side of the sofa until it reaches Position R when it will again follow the initial traverse around the room.

Information representative of the level of light detected at each change of direction point (referred to as a way point) will be stored in memory together with information from the four main ultrasonic receivers 29. When the machine returns to similar way points, e. g. way points B, I and T or way points C and J, information on the two points will be associated with one another in memory in order to build up an information strand. This will tell the cleaner that it has returned to a known point and will also tell the cleaner when the floor of the room, apart from areas occupied by obstacles, has been cleaned.

If the robotic vacuum cleaner is initially placed in the middle of the room, it will travel until it finds a wall or obstacle. If it finds a wall it will then follow the path described above. If it finds a feature (such as a central fireplace) or an obstacle in the centre of the room, it will complete a circuit around that feature or obstacle and then follow a generally outwardly spiral path.

The methods of operation described above are believed to be more efficient ways of cleaning a room than have hitherto been proposed. Also, the cleaner is fully autonomous and does not need to be fed a detailed map of the room and/or trained. The memory may be wiped on Power Off so that information stored is not retained for future use. Alternatively, the information could be stored for future use in the same room.

Claims

CLAIMS 1. A method of operating a robotic floor cleaning device so that the floor cleaning device (a) firstly completes a traverse around the edge of a room (or around a feature of the room or an object in the room) avoiding any obstacles in its path, and (b) then moves inwards (or outwards) by, or substantially by, the width of the cleaning device and completes a second traverse, the cleaning device continuing to move inwards (or outwards) by, or substantially by, the width of the cleaning device after each traverse so as to travel in a generally inwardly (or outwardly) spiral manner until the floor of the room, apart from areas occupied by obstacles, has been cleaned.
2. A method as claimed in claim 1, wherein information representative of the level of ambient light is stored in memory each time the cleaning device changes direction upon reaching a room feature and the level of light is periodically monitored and compared with previously stored information so that the cleaning device can identify when the level of light is the same or substantially the same as a level previously stored to indicate that the cleaning device should change direction and/or move inwards (or outwards) by or substantially by the width of the cleaning device.
3. A method as claimed in claim 2, wherein information received from a plurality of ultrasonic sensors is also stored in memory each time the cleaning device changes direction and signals from the sensors are periodically monitored and compared with previously stored information.
4. A method as claimed in claim 2 or claim 3, wherein the information stored in memory at each said change of direction of the cleaning device during the second and any subsequent traverses of the room is associated with information previously stored for that position in the room.
5. A method as claimed in any one of claims 1 to 4, wherein information indicative of the direction in which the cleaning device turns at each said change of direction is stored in memory at least during the initial traverse.
6. A method of operating a robotic floor cleaning device substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.
7. A robotic floor cleaning device comprising power operated means for moving the cleaning device along the floor and a navigation system for identifying the location of the cleaning device in a room and for navigating the cleaning device around the room, the cleaning device being programmed so that it firstly completes a traverse around the edge of a room (or around a feature of the room or an object in the room) avoiding any obstacles in its path and then moves inwards (or outwards) by, or substantially by, the width of the cleaning device after each completed traverse until the floor of the room, apart from areas occupied by obstacles, has been cleaned.
8. A robotic floor cleaning device as claimed in claim 7, wherein the navigation system includes a light detector for detecting the level of light, memory means for storing information representative of the level of light each time the cleaning device changes direction upon reaching a room feature and means for comparing the level of light with previously stored information so that the cleaning device can identify when the level of light is the same or substantially the same as a level previously stored to indicate that the cleaning device should change direction and/or move invars (or outwards) by, or substantially by, the width of the cleaning device.
9. A floor cleaning device as claimed in claim 8, wherein the light detector provides signals representative of the level of light received from a plurality of different compass points around the cleaning device.
10. A floor cleaning device as claimed in claim 8 or claim 9, wherein the memory means is also for storing information indicative of the direction in which the cleaning device turns at least during an initial traverse.
11. A floor cleaning device as claimed in any one of claims 7 to 10, wherein the navigation system also comprises a plurality of sensors for detecting obstacles and corners of the room.
12. A floor cleaning device as claimed in any one of claims 7 to 11, wherein the sensors include a plurality of ultrasonic sensors and the memory means also stores information received from these ultrasonic sensors.
13. A floor cleaning device as claimed in any one of claims 7 to 12, wherein the power operated means comprises two ground engageable wheels and two electric motors for driving the two wheels, respectively.
14. A floor cleaning device substantially as hereinbefore described with reference to the accompanying drawings.
15. A floor cleaning device as claimed in any of claims 7 to 14, in the form of a robotic vacuum cleaner.