US 20060229765 A1
An electric machine, such as an autonomous vacuum cleaner, is powered through a cable and includes a means or device for detecting the orientation of the cable with respect to the main body of the machine that may be in the form of a pivotable member such as pendulum, connected to a potentiometer. The potentiometer provides an output signal proportional to the position of the free end of the pendulum. Thus, the machine can detect the position of the cable and thus can avoid it or else follow it. Microswitches may also be provided to detect extreme positions of the cable.
1. An autonomous machine comprising a main body, a power cable and a device for detecting the orientation of the cable with respect to the main body.
2. An autonomous machine as claimed in
3. An autonomous machine as claimed in
4. An autonomous machine as claimed in
5. An autonomous machine as claimed in 4, in which the pivotable member comprises a pendulum, one end portion of which is associated with the cable, the other end portion of which is associated with the rotary encoder.
6. An autonomous machine as claimed in
7. An autonomous machine as claimed in
8. An autonomous machine as claimed in
9. An autonomous machine as claimed in
10. An autonomous machine as claimed in
11. A vacuum cleaner comprising the autonomous machine of
13. A method of operating an autonomous machine comprising a main body and a power cable, comprising detecting the orientation of the cable with respect to the main body.
14. A method as claimed in
15. A method as claimed in
16. A method as claimed in
18. An autonomous machine as claimed in
19. An autonomous machine as claimed in
20. A vacuum cleaner comprising the autonomous machine of
21. A vacuum cleaner comprising the autonomous machine of
22. A vacuum cleaner comprising the autonomous machine of
23. A vacuum cleaner comprising the autonomous machine of
24. A vacuum cleaner comprising the autonomous machine of
This invention relates to an autonomous machine powered by a power cable, for example a robotic vacuum cleaner.
There have been various proposals to provide autonomous or robotic machines for performing duties such as cleaning or polishing a floor area, or for mowing grass. Some autonomous machines are capable of exploring the environment in which they are placed without human supervision, and without advance knowledge (e.g. a map) of the layout of the environment. The machine may explore the environment during a learning phase and will subsequently use this information during a working phase, or the machine may begin working in the area immediately. Autonomous machines of this type are particularly attractive to users as they can be left to work with minimal human supervision.
It is also known to provide autonomous machines which derive their power from a mains power supply and which carry a reel of cable which is dispensed as the machine moves around the area. U.S. Pat. No. 4,962,453 shows an example of this kind of machine, which covers a working area by a complex series of fan-shaped coverage patterns.
A problem which may be encountered with cable-powered machines is that the cable itself can hamper the functioning of the machine. For example, if an autonomous machine runs over its own cable, it may experience odometry errors or may damage the cable.
The invention provides an autonomous machine comprising a main body, a power cable and means for detecting the orientation of the cable with respect to the main body
The invention permits the machine to detect the position of its own cable. The machine may therefore be controlled so as to avoid or to follow its own cable.
Preferably, the means for detecting cable orientation comprises a first detecting means arranged to detect the orientation of the cable within a first predetermined range. A second detecting means arranged to detect the orientation of the cable within a second predetermined range may also be provided. The first and second ranges may be separate or may overlap.
Advantageously, the first detecting means comprises a rotatable member connected to a rotary encoder such as a potentiometer. A suitable rotatable member is a pendulum, one end portion of which is connected to the cable, the other end portion of which is associated with the encoder.
The second detecting means may comprises one or more pressure switches, such as microswitches, arranged adjacent the cable, to produce a signal when the cable pushes against it. Alternatively, an intermediary member such as a collar around the cable may be arranged to push against the switches when the cable is deflected.
The machine can take many forms: it can be a floor treating machine such as a vacuum cleaner or floor polisher, a lawn mower or a robotic machine which performs some other function. Alternatively, it could be a general purpose robotic vehicle which is capable of carrying or towing a work implement chosen by a user.
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:—
The machine comprises a main body or supporting chassis 12, two driven wheels 15, a cleaner head 40, a user interface with buttons 60 and indicator lamps 65 and various sensors 20-26, 30 for sensing the presence of objects around the machine. Also mounted on the chassis 12 is apparatus 14 for separating dirt, dust and debris from an incoming airflow and for collecting the separated material, a reel for storing a length of power cable 95, and a system for dispensing and rewinding the power cable. The machine 10 is supported on the two driven wheels 15 and a castor wheel (not shown) at the rear of the machine. The driven wheels 15 are arranged at either end of a diameter of the chassis 12, the diameter lying perpendicular to the longitudinal axis of the cleaner 10. The driven wheels 15 are mounted independently of one another via support bearings (not shown) and each driven wheel 15 is connected directly to a traction motor 16 which is capable of driving the respective wheel 15 in either a forward direction or a reverse direction. A full range of manoeuvres is possible by independently controlling each of the traction motors 16.
Mounted on the underside of the chassis 12 is a cleaner head 40 which includes a suction opening facing the surface on which the cleaner 10 is supported. A brush bar 45 is rotatably mounted in the suction opening and a motor 48 is mounted on the cleaner head 40 for driving the brush bar 45. It will be appreciated that the brush bar 45 could be omitted, if desired, so that the cleaner head 40 only has a suction opening and cleans by relying on suction alone. For other types of surface treating machine, the cleaner head 40 could be replaced by a polishing pad, wax dispenser, squeegee etc.
The chassis 12 of the machine 10 carries a plurality of sensors 20-26, 30 which are positioned on the chassis 12 such that the navigation system of the machine can sense obstacles in the path of the machine 10 and also the proximity of the machine to a wall or other boundary such as a piece of furniture. The sensors shown here comprise several ultrasonic sensors 20-26 which are capable of sensing the distance and angular position of walls and objects from the sensors, and several passive infra red (PIR) sensors 30 which can sense the presence of humans, animals and heat sources such as a fire. There are forward-facing sensors 22, 23, side-facing sensors 20, 21 and 24, 25, rear-facing sensors (not shown) and high-level sensors 26. It will be appreciated that the number of sensors, type of sensors and positioning of the sensors on the machine 10 can take many different forms. For example, infra red range-finding devices, also known as PSDs, may be used instead of, or in addition to, the ultrasonic sensors 20-26. In an alternative embodiment the machine may navigate by mechanically sensing the boundary of the working area and boundaries of obstacles placed within the area. One example of a mechanical sensor which could be used on a machine of this type is a “bump” sensor which detects movement of a moveable or resilient bumper when the machine encounters an obstacle. “Bump” sensors can be used in combination with the ultrasonic and PIR sensors described above.
One or both sides of the vehicle can also have an odometry wheel 18. This is a non-driven wheel which rotates as the machine moves along a surface. Each odometry wheel 18 has an encoder associated with it for monitoring the rotation of the odometry wheel 18. By examining the information received from each odometry wheel 18, the navigation system can determine both the distance travelled by the machine and any change in angular direction of the machine. It is preferred that the odometry wheel 18 is a non-driven wheel as this increases the accuracy of the information obtained from the wheel. However, in a simpler embodiment, the machine can derive odometry information directly from the driven wheels 15, by an encoder located on the wheel 15 or the motor 16 which drives the wheel 15.
The machine 10 also includes a motor 52 and fan 50 unit supported on the chassis 12 for drawing dirty air into the machine via the suction opening in the cleaner head 40.
The electrical systems for the machine, shown in detail in
There are various ways of managing cable storage on the machine.
In accordance with the invention, means are provided to indicate the orientation of the cable with respect to the chassis. After passing through the pinch rollers 70, the cable 95 passes through an opening 75 in the free end of a pivotable member in the form of a pendulum 74. The pendulum 74 is pivotable about a shaft 73, the pendulum 74 being movable in a vertical plane. Shaft 73 forms part of a rotary encoding device 76, such as a potentiometer, which can provide an output signal proportional to movement of the pendulum 74.
As shown in
In the situation shown in
The operation of the machine will now be described with reference to FIGS. 4 to 9.
FIGS. 5 to 9 show the machine 10 at work, in a room of a house. The boundary of the working area for the machine is defined by the walls of the room 301-304 and the edges of objects 305-308 placed within the room, such as articles of furniture (e.g. sofa, table, chair). These figures also show the set of paths 320 traversed by the machine.
The machine 10 is placed in the room by a user. Ideally, the machine is left near to a power socket 310 in the room, with the plug inserted into the socket 310 and a short length of power cable lying on the floor between the socket and the machine 10. Once the machine has been switched on, it begins a short routine to discover a starting or ‘home’ position in the room (step 110). The power socket 310 is a convenient home position for the mains powered machine. The ‘home’ position serves as a useful reference point for determining, inter alia, when the machine has travelled around the entire room. The machine determines the position of the power socket 310 by winding the cable 95 onto its internal cable reel 71 as it reverses. The machine can find the socket 310 by mechanically sensing that the cable 95 has been fully rewound, or by detecting a marker 98 placed on the cable 95, near to the plug. The machine then aligns its left hand side with the boundary of the area and starts the suction motor 52 and brush bar motor 48. It waits until the motors 48, 52 reach operating speed and then moves off. As the cleaner moves forwards (step 115) it dispenses power cable 95 from the cable reel so that the cable lies substantially along the path taken by the machine 10. Due to the potential for odometry errors, the cable 95 may be dispensed at a rate which is slightly higher than the rate of movement of the machine 10.
The machine then begins a series of manoeuvres. The series of manoeuvres may comprise, for example, random movements, a spiral pattern, a so-called ‘spike’ pattern, or any combination of movement types. which in combination will be referred to as a ‘spike’. The basic spike is shown in
Once the machine has stopped, having met one or more of the conditions mentioned above, it reverses back towards the boundary following a similar path 332 (step 135,
During the return manoeuvre, the machine can navigate towards the boundary by using odometry information or it can follow the cable 95 which was laid on the floor during the outward trip, the process previously described as ‘cable follow mode’. Thus, the machine detects the orientation of the cable with respect to the chassis and follows the cable accordingly. This outward trip into the working area and back again to the boundary constitutes the previously mentioned ‘spike’.
As the length of the outward part of the spike increases, the likelihood that the machine will drift from the intended path also increases. Odometry errors, wheel slippage, changes of surface material and the direction of carpet pile are some factors which can cause the machine to drift from an intended path. In the unlikely event that the outward and return paths of the spike are spaced apart and an object lies between the paths, then there is a risk that the power cable can become wrapped around the object. In these circumstances, it is preferable for the machine to navigate back to the boundary in the cable follow mode (steps 137, 138).
Once the machine has returned to the boundary, which it can sense from its sensor array and odometry information, it turns so that it is once again pointing in a clockwise direction, with its left-hand side aligned with the boundary. It moves forwards for a short distance which is sufficient to bring the machine next to the strip of the floor which has just been treated. The cleaner then turns so that it is again pointing away from the boundary, inwards into the working area. The machine then travels forwards at an angle which is substantially perpendicular to the boundary, as before. The machine continues as previously described, traversing a strip of the floor surface which is adjacent, or overlaps, the area previously treated.
The machine repeats this sequence of steps so as to traverse a plurality of paths extending into the working area from the boundary, as can be seen in
After completing each spike, the machine checks whether it has covered the entire working area (step 140). This check can be performed in various ways. In its simplest form, the machine can use an on-board sensor to sense whether it has returned to a starting position on the boundary. Preferably, a marker 98 is provided on the power cable 95 at a position adjacent the plug so that the machine can sense when it has returned to this position. The marker 98 can be a magnetic marker and the machine can be provided with a magnetic field sensor, such as a Hall-Effect sensor, for sensing the marker. Alternatively, the machine generates a map of the working area and updates this map so as to record areas of floor visited by the machine. Thus, by using this map, the machine can determine when it has completely covered the working area. After each spike the machine also checks (step 145) to ensure that it has sufficient cable 95 remaining on the cable reel 71 to continue travelling around the boundary.
Step 145 requires the machine to have the capability to detect the amount of cable 95 remaining on the cable reel 71. This can be achieved by marking the cable 95 in a manner which indicates the quantity of remaining cable 95 and providing the control system with a sensor which can detect the markings. Alternatively, an encoder on the pinch roller 70 can feed the control system with an indication of the amount of cable 95 dispensed from the reel 71. This is advantageous because the same mechanism can be used to detect any jamming of the cable 95. In a simpler machine this step can be omitted entirely and the machine can simply stop when all of the cable 95 has been dispensed from the reel 71, wherever this may be in the room.
If the machine determines that it has completely covered the working area, it travels back to the starting position in the working area. The machine can follow the boundary of the working area, rewinding the cable 95 as it moves around the boundary. Alternatively, the machine can operate in cable follow mode, rewinding the cable 95 and following the path formed by the cable 95 on the surface of the working area. In the event that this brings the machine near to an obstacle, the machine can revert to a boundary following mode of operation until it is determined that the cable 95 leads away from the obstacle, whereupon the machine can once again operate in cable follow mode. The machine will eventually return to the starting point near to the power socket 310.
In large working areas the machine may run out of cable before it has completely covered the working area. In this case, the machine proceeds to perform the same technique as has previously been described in the opposite direction from the starting point (step 170,
For the machine accurately to detect when it has returned to a point where cleaning finished previously (such as point X), it requires some form of mapping function. The machine needs to have the capability to map the working area and record where it has visited in the working area. The map can be constructed using odometry information which is acquired from the odometry wheels 18 and/or information about features of the working area which is acquired from the object detection sensors 20-26, 30 in a manner which is known in the art. The machine can then use the map to determine when it has returned to a point on the boundary which it previously reached via a journey in the opposite direction around the boundary. It is preferable to allow a good overlap region, as accumulated odometry errors can cause some error between the actual position of the machine, and the position of the machine as determined by the map.
If the machine lacks any form of mapping function, then it can simply continue to work in the opposite direction around the working area until the cable has all been dispensed. This can result in a considerable region where the surface is treated twice.
Alternative embodiments of the invention are shown in
A further alternative is shown in
Further variations may be made without departing from the scope of the invention. For example, the machine need not employ a cable-follow operation. Alternatively, or additionally, the machine may employ signals from the rotary encoder and/or pressure switches in order to avoid running over its own cable or somehow getting tangled in the cable.