1. Field of the Invention
The present invention relates to an autonomous vacuum cleaner.
2. Description of the Related Art
In a conventional autonomous vacuum cleaner for cleaning a floor surface, floor sensors are used to check the floor surface where the vacuum cleaner moves around and sweeps. For example, such a floor sensor is known which comprises an ultrasonic sensor transmitting an ultrasonic signal to the floor surface and receiving the ultrasonic signal reflected from the floor surface, which is used in a manner that the ultrasonic signal reciprocating between the ultrasonic sensor and the floor surface plural times is integrated by an integrating circuit, and the level of the integrated signal is determined to identify the kind of the floor surface, and to control the operation of a power brush dedicated to carpet cleaning (refer to e.g. Japanese Patent No. 2820407).
Further, a floor sensor is known which comprises an ultrasonic sensor mounted on the front of a drive unit of a vacuum cleaner, which functions as both a step detecting means and a floor surface identifying means, that is, the sensor detects steps on the floor if exist, and at the same time discriminates a carpeted floor from a bare floor based on reflection conditions of the floor surface for the ultrasonic signal (refer to e.g. Japanese Laid-open Patent Publication No. 2003-116756).
However, according to such floor sensors using an ultrasonic sensor as disclosed in the patent references above, it is possible to obtain magnitude information of only averaged reflectivity (or absorptivity) of the ultrasonic signal on the floor surface. Thus there still exists a problem that it is not possible to accurately identify the material or kind of the floor surface.
An object of the present invention is to provide such an autonomous vacuum cleaner comprising a floor sensor of simple structure which can detect a step on a floor surface and also can accurately identify the material of the floor surface by using one same floor sensor, thereby enabling meticulous cleaning.
According to the present invention, the above object is achieved by an autonomous vacuum cleaner comprising:
According to this autonomous vacuum cleaner of the present invention, signals received by the passive-type line sensor, which has a higher resolution than e.g. an ultrasonic sensor, are subjected to calculation when the cleaner moves autonomously by avoiding obstacles detected by the obstacle detection sensor and by recognizing the self-position and cleans a predetermined area, whereby a distribution of distances to the floor surface is derived more accurately than the prior art. Since the moving means and the cleaning means are controlled on the basis of thus derived or calculated distance distribution to the floor surface, the cleaner can clean efficiently and move stably in accordance with the condition of the floor surface.
Preferably, the autonomous vacuum cleaner further comprises a floor surface identifying means to identify material of the floor surface on the basis of the distance distribution derived by the floor surface distance calculating means, wherein the moving means and the cleaning means are controlled depending on the material of the floor surface identified by the floor surface identifying means.
According to this preferred mode, the moving means and the cleaning means are controlled further depending on the material of the floor surface, thereby enabling more meticulous operation for desired cleaning results.
Further preferably, the passive-type line sensor is of CMOS, and the cleaning means includes:
According to this further preferred mode, signals received by the CMOS passive-type line sensor, which has a higher resolution and more simple structure than e.g. an ultrasonic sensor, are subjected to calculation and an accurate distance distribution is obtained which enables more detailed control of the moving means and the cleaning means. The cleaning means can clean powerfully with a power brush and a nozzle of wide extension.
Further preferably, the autonomous vacuum cleaner further comprises a cleaning condition changing means to change cleaning conditions including at least one of the moving speed of the cleaner, dust suction force of the suction fan, or brushing strength of the power brush on the basis of the floor material identification made by the floor surface identifying means during the cleaning,
According to this further preferred mode, it is possible to identify the material of the floor (polished floorboard, tatami, or carpet) more accurately than the prior art. And it is also possible to detect a step on the floor surface with the same sensor used for floor surface identification, thereby enabling reduction of sensor cost.
Furthermore, since the material of the floor surface can be accurately identified, it is possible to protect the floor surface from damage by changing the cleaning conditions depending on the kind of the floor surface material, and possible to efficiently realize cleaned state of the floor surface as desired.
While the novel features of the present invention are set forth in the appended claims, the present invention will be better understood from the following detailed description taken in conjunction with the drawings.
The present invention will be described hereinafter with reference to the annexed drawings. It is to be noted that all the drawings are shown for the purpose of illustrating the technical concept of the present invention or embodiments thereof, wherein:
An autonomous vacuum cleaner according to an embodiment of the present invention will be described hereinafter with reference to the annexed drawings.
As shown in
The autonomous vacuum cleaner 1 comprises a ceiling sensor 21 and front sensors 22. Those are optical distance sensors for detecting e.g. obstacles for the cleaner 1 to move autonomously, and which are provided on a projecting portion on an upper surface of the cleaner-upper-part 1a as shown in
The cleaner-upper-part 1a of the autonomous vacuum cleaner 1 comprises a control device box 10, inside of which (not shown) a geomagnetic sensor 24 and an acceleration sensor 25 are provided for the cleaner 1 to move autonomously. The acceleration sensor 25 independently detects accelerations acting on the cleaner 1 as it moves in three directions of up-down, forward-backward and left-right, respectively. The geomagnetic sensor 24 outputs signals correlated with the direction of the geomagnetic field to decide the direction in which the cleaner 1 faces.
As shown in
Inside the control device box 10 shown in
Now, the following describes the autonomous movement of the autonomous vacuum cleaner 1. The movement control unit 13 controls the left and right drive motors 31 under the control of the central control means 11 so as to control the rotational directions and the rotational speeds of the left and right drive wheels 32, thereby controlling the movement of the cleaner 1. The autonomous vacuum cleaner 1 moves with reference to the map information 12 to perform the cleaning operation, and the map information 12 is renewed during the cleaning operation.
The movement control unit 13 creates map information, based on outputs of the ceiling sensor 21, the front sensors 22 and the floor sensors 5 (5a and 5b), about the area where any obstacle exists and also about the area cleaned already, and then store the information in a memory as the map information 12. The movement control unit 13 recognizes, under the control of the central control means 11, the self-position of the autonomous vacuum cleaner 1 by calculating a moving distance and self-position coordinate values of the cleaner 1, based on a moving speed obtained by time-integration of the acceleration values in the forward-backward direction detected by the acceleration sensor 25, and based on a separately measured moving time, and further based on posture direction information from the geomagnetic sensor 24.
The autonomous vacuum cleaner 1 further comprises, on the cleaner-upper-part 1a as shown in
The autonomous vacuum cleaner 1 furthermore has a security function for monitoring e.g. intruders. For this function, the cleaner 1 comprises, on an outer periphery of the cleaner-upper-part 1a as shown in
Next, the cleaning function of the autonomous vacuum cleaner 1 will be described. The autonomous vacuum cleaner 1 comprises, as shown in
The nozzle 44 has a nozzle opening 44a which faces a contact portion of the power brush 41 and the driven roller 41b. The power brush 41 is rotated by the brush motor 41a to brush floor surface F from back to front in the moving direction, and to move dust on the floor surface F forward and upward. The nozzle 44 sucks up, from the nozzle opening 44a, both the dust gathered up by the power brush 41 and the dust transported by the driven roller 41b, and exhausts the dust into the dust box 43. The suction fan 42 has a suction inlet which is connected to the dust box 43 via a filter (not shown), so that the sucked dust is collected by the dust box 43. The nozzle opening 44a opens elongated in a direction of the width of the autonomous vacuum cleaner 1 (left-right direction), i.e. perpendicular to the moving direction Z. Besides, the nozzle opening 44a has a valve 44b which is capable of being opened and closed by the suction force in order to prevent the dust from falling when not sucked.
Next, the function of the autonomous vacuum cleaner 1 to identify the material of the floor surface will be described. The autonomous vacuum cleaner 1, in addition to the floor sensors 5, comprises a floor surface distance calculating means 6, a floor surface identifying means 7 and a cleaning condition changing means 8, which are related to the function. Those means are formed by software, and are stored in a memory device in the control device box 10 shown in
The following describes the structure and the function of the floor sensors 5. As shown in
The inner structure of each of the floor sensors 5 will be described in the following.
As shown in
The coordinate of each of the above focused image points can be derived from the variation of received light intensity I as shown in
A way of identifying presence of a step on a floor and also identifying material of the floor will be described below.
Those of distance distributions derived above are processed to identify floor conditions as follows. For example the distance distribution of
Those identification results coincide with results obtained by ordinary visual and sensory observation, that is, a polished floorboard is observed to have a substantially constant distance distribution within substantially entire range of distance measurement, and a tatami is observed to have a constantly repeated uneven distance distribution, and a carpet is observed to have a distance distribution composed of shorter distances than in the case of polished floorboard and further a carpet is observed to have an irregular distance distribution within distance measuring range. These spatial frequency analysis and identification are performed by the above-described floor surface identifying means 7. As evident from the above, the floor sensor 5 can be used as both a step detection sensor and a floor surface identification sensor.
When the material of the floor is identified by the floor surface identifying means 7, cleaning conditions including at least the moving speed, the dust suction force of the suction fan 42 or the brushing strength of the power brush 41 are changed by the cleaning condition changing means 8 on the basis of the result of the identification made by the floor surface identifying means 7 during the time the autonomous vacuum cleaner 1 moves while cleaning. Thereby, it becomes possible to efficiently perform desired cleaning of floor surface without damaging the floor surface. Such change of the cleaning conditions is made by the above-described cleaning condition changing means 8.
Hereinafter, referring to the flow chart of
Subsequently, the floor sensors 5 receive light reflected from a floor surface (S5) and output received signals, which are input to the floor surface distance calculating means 6 and the means 6 derives a calculated distance distribution by calculation (S6). Thereafter, the floor surface identifying means 7 performs a pre-process of identifying the floor surface such as detection of distance variation and analysis of spatial frequency in the calculated distance distribution (S7). Subsequently, the floor surface identifying means 7 performs a series of comparisons and identifications as follows. First, if the distance variation in the calculated distance distribution is larger than a predetermined value (YES in S8), it is concluded that there is a step on the floor surface (S9), and then the autonomous vacuum cleaner 1 performs step avoidance operation by using the movement control unit 13 via the central control means 11 (S10).
If the distance variation is smaller than or equal to the predetermined value (NO in S8), the floor surface identifying means 7 performs a comparison and identification based on a main frequency in the spatial frequency spectrum in the distance distribution. If the main spatial frequency is substantially zero (YES in S11), the material of the floor surface is identified as a polished floorboard Based on this result, the cleaning condition changing means 8 sets the cleaning means to be for polished floorboard (S12).
If the material of the floor surface is not identified as a polished floorboard (NO in S11), a subsequent comparison and identification is performed, that is, if the main spatial frequency is lower than or equal to a predetermined value (YES in S13), the material of the floor surface is identified as a tatami. Based on this result, the cleaning condition changing means 8 sets the cleaning means to be for tatami (S14). Similarly, if the material of the floor surface is not identified as a tatami (NO in S13), a subsequent comparison and identification is performed, that is, if the main spatial frequency is higher than the predetermined value (YES in S15), the material of the floor surface is identified as a carpet. Based on this result, the cleaning condition changing means 8 sets the cleaning means to be for carpet (S16).
After the above series of identifications and cleaning condition settings are completed, the map information 12 is referred to see whether the cleaning for the predetermined cleaning area being completed or not, and if completed the cleaning process ends (YES in S17). On the other hand, if the cleaning is not completed (NO in S17), the above steps from step S2 onward are repeated. The central control means 11 of the autonomous vacuum cleaner 1 repeats these steps at predetermined time intervals to perform the cleaning process.
It is to be noted that the present invention is not limited to the above described structures, configurations or processes, and various modifications are possible. For example, without using the floor sensor 5 both as step detection and floor surface identification, separate exclusive sensors, i.e. not dual-purpose sensors, can be used for step detection and floor surface identification, respectively. Furthermore, the mounting positions and the sensing directions of the above-described various sensors are not limited to those illustrated above.
This application is based on Japanese patent application 2004-022408 filed in Japan dated Jan. 30, 2004, the contents of which are hereby incorporated by reference.
The present invention has been described above using presently preferred embodiments, but such description should not be interpreted as limiting the present invention. Various modifications will become obvious, evident or apparent to those ordinarily skilled in the art, who have read the description. Accordingly, the appended claims should be interpreted to cover all modifications and alterations which fall within the spirit and scope of the present invention.
Number | Date | Country | Kind |
---|---|---|---|
2004-022408 | Jan 2004 | JP | national |