Robot cleaner and control method thereof

1. A robot cleaner comprising:

a main body;

a traveling assembly configured to move the main body;

a cleaning tool assembly installed in the main body, and including a pad configured to adsorb water, and to contact a surface to clean the surface by applying the adsorbed water from the robot cleaner to the surface using a motion of the pad;

a water-feeder to directly supply the water from the water-feeder to the cleaning tool assembly to first be adsorbed by the pad and then applied from the pad to the surface;

a capacitance measurer installed in the main body, to contact the pad of the cleaning tool assembly so that the pad overlaps the capacitance measurer by a predetermined overlapping thickness, and configured to measure a capacitance of the cleaning tool assembly that changes based on an amount of the adsorbed water in the pad; and

a controller configured to determine the amount of the adsorbed water in the pad based on the measured capacitance and control the robot cleaner based on the determined amount of the adsorbed water in the pad,

wherein the capacitance measurer comprises:

a housing including a container having a first side having an outer surface contacting the pad of the cleaning tool assembly and second sides extending from edges of the first side;

a cover to cover the housing;

a Printed Circuit Board (PCB) substrate disposed in the container of the housing and adjacent to an inner surface of the first side of the housing; and

a first sensor disposed on a first surface of the PCB substrate and adjacent to the inner surface of the first side of the housing, the first sensor configured to measure the capacitance of the cleaning tool assembly that changes based on the amount of the adsorbed water in the pad.

2. The robot cleaner according to claim 1 , wherein the capacitance measurer further comprises a second sensor disposed on a second surface of the PCB substrate, the second surface being opposite to the first surface of the PCB substrate on which the first sensor is disposed, the second sensor measuring a reference capacitance of an inner space of the container of the housing.

3. The robot cleaner according to claim 1 , wherein the capacitance measurer further comprises a sealing member disposed between the first side of the housing and the first sensor to prevent an air gap from being formed between the first side of the housing and the first sensor, thereby preventing the first sensor from contacting air.

4. The robot cleaner according to claim 1 , wherein the first side of the housing of the capacitance measurer has a thickness ranging from approximately 0.5 mm to approximately 1.5 mm.

5. The robot cleaner according to claim 1 , wherein the housing of the capacitance measurer protrudes toward the cleaning tool assembly.

6. The robot cleaner according to claim 1 , wherein the capacitance measurer further comprises a close-contacting member which is disposed between the cover and the PCB substrate, and which applies pressure to the PCB substrate for the PCB substrate to closely contact the first side of the housing.

7. The robot cleaner according to claim 1 , wherein the cleaning tool assembly comprises:

a drum rotatably coupled to the main body, wherein the pad is attached to an outer surface of the drum; and

a gear member which is connected to an end of the drum, and configured to rotate the drum.

8. The robot cleaner according to claim 7 , wherein:

the pad attached to the outer surface of the drum has a predetermined curvature, and

the first side of the housing of the capacitance measurer has a curvature corresponding to the predetermined curvature of the pad.

9. The robot cleaner according to claim 1 , wherein the water-feeder comprises:

a water tank which is removably coupled to the main body, and configured to store water;

a pump which is connected to the water tank, and configured to pump water stored in the water tank; and

a channel member which is connected to the pump, and configured to guide the pumped water to the cleaning tool assembly.

10. The robot cleaner according to claim 9 , wherein:

the channel member comprises a first channel and a second channel which divide water pumped by the pump and which guide the pumped water to the cleaning tool assembly, and

the main body comprises an insertion hole into which the capacitance measurer is inserted and installed, and a plurality of water-feeding holes spaced by a predetermined distance from the inserting hole, wherein the first and second channels are inserted into the plurality of water-feeding holes.

11. The robot cleaner according to claim 10 , wherein the capacitance measurer is detachable from the main body.

12. The robot cleaner according to claim 9 , further comprising:

a water-feeding hole into which the channel member is inserted; and

a spraying member which is connected to the water-feeding hole, and configured to supply water to the cleaning tool assembly by spraying water from the water-feeding hole onto the cleaning tool assembly.

13. The robot cleaner according to claim 12 , wherein the capacitance measurer is further protruded toward the surface than the spraying member.

14. The robot cleaner according to claim 1 , wherein the predetermined overlapping thickness is between a minimum overlapping thickness at which no air gap is formed between the outer surface of the housing of the capacitance measurer and the pad of the cleaning tool assembly and a maximum overlapping thickness corresponding to a thickness of the pad of the cleaning tool assembly.

15. A robot cleaner comprising:

a main body;

a traveling assembly configured to move the main body;

a cleaning tool assembly installed in the main body, and including a pad configured to adsorb water, and to contact a surface to clean the surface by applying the adsorbed water from the robot cleaner to the surface using a motion of the pad;

a water-feeder to directly supply the water from the water-feeder to the cleaning tool assembly to first be adsorbed by the pad and then applied from the pad to the surface;

a capacitance measurer installed in the main body, to contact the pad of the cleaning tool assembly, and configured to measure a capacitance of the cleaning tool assembly that changes based on an amount of the adsorbed water in the pad; and

a controller configured to determine the amount of the adsorbed water in the pad based on the measured capacitance and control the robot cleaner based on the determined amount of the adsorbed water in the pad,

wherein the capacitance measurer contacts the pad of the cleaning tool assembly so that the pad overlaps the capacitance measurer by a predetermined overlapping thickness.

16. The robot cleaner according to claim 15 , wherein the pad of the cleaning tool assembly is rotatable.