The present invention relates to a robot cleaner and method for controlling the same.

Known robot cleaners for cleaning a floor surface include a traveling unit configured to move a vacuum body to travel and a suction section unit to suck dust and the like into a dust collection box in the vacuum body through a suction port. The traveling unit includes usually a pair of right and left wheels and two motors configured to drive each wheel in a forward rotation direction and a reverse rotation direction. The traveling unit causes the vacuum body to travel in a front-back direction, and turns the vacuum body in an optional direction. The suction unit includes a duct and an air blower communicating with the suction port, and a rotary brush provided at the suction port. The suction section is configured to suck, through the suction port, dust and the like scraped off by the rotary brush. The robot cleaner intelligently vacuums an area by sucking dust or foreign materials from the floor surface while moving around the area in a self-guided and propelled manner. While moving the robot cleaner detects obstacles in the cleaning area with various sensors, and controls a running path and cleaning operations of the robot cleaner based on the result of the detecting of the obstacles.

The patent document EP3636128A1 discloses the self-propelled vacuum configured so that depending on an obstacle, the self-propelled vacuum can move over the obstacle without performing avoidance operation to shorten cleaning time. A self-propelled vacuum includes a vacuum body, a suction unit for sucking dust and the like on a floor surface F, a traveling drive unit configured to drive wheels, a front sensor configured to sense an obstacle S in the front in a traveling direction, and a vehicle height adjustment unit configured to move the wheels up and down to adjust the vehicle height of the vacuum body. In a case where the traveling drive unit is driven and the front sensor senses the obstacle during self-propelling, the vehicle height adjustment unit increases the vehicle height to a predetermined height, and thereafter, the self-propelled vacuum moves over the obstacle while the vehicle height is being adjusted such that a distance to the obstacle is held within a predetermined range. The patent document EP2921095A1 discloses the robot cleaner which includes a main body forming an exterior, a floor detection sensor for detecting a distance from the main body to a floor surface, a tilt sensor for detecting inclination of the main body, and a controller for determining whether there is a protruding part that protrudes from a floor surface in a running path of the main body, based on a first sensor value output by the floor detection sensor and a second sensor value output by the tilt sensor. In accordance with embodiments of the present disclosure, a robot cleaner may properly move around and perform vacuuming by taking into account conditions of a floor surface. It may also smoothly climb over a doorsill and dynamically change its running pattern based on the presence/absence and position of an obstacle in climbing the doorsill. The front of the robot cleaner is provided with the caster wheel to help stabilize the main body and designed in such a way that the robots climb obstacles that are within their ability to overcome. A suction mouth placed at the front or a cleaning cloth that reaches to the floor are not possible in these places.

The patent document W02017194101A1 discloses the method of adjusting the height of a robotic cleaning device over a surface across which the robotic cleaning device moves, comprising receiving a signal indicative of a need to adjust the height of the robotic cleaning device over the surface, and controlling, in response to the received signal, at least one actuator configured to adjust the height of the robotic cleaning device in accordance with the indicated need. Robotic cleaning device performing said method. The robotic cleaner can extend its drive wheels (and support wheels) out of the robot. In this way, the robot achieves greater ground clearance and can overcome higher obstacles. A ramp that can help climbing on the doorsill would not be necessary with this concept, so that the suction nozzle or cleaning cloths can also be positioned close to the front. The mechanism for extending the drive wheels however the structure of the mechanism is complex.

An object of the present invention is to provide a cleaning robot that is capable to overcome obstacles in the way adapted to the type of obstacle, so as to reduce the cleaning time, and which is more durable and reliable. It is another object of the present invention is collecting with the robot cleaner more accurate environmental data that allows for improved obstacle overcoming and underfurniture cleaning.

It is another object of the present invention to provide a method for controlling the robot cleaner that overcomes different kinds of obstacles.

In accordance with the present invention, there is provided a robot cleaner comprising: a housing with a lower portion, an upper portion, a front portion, a rear portion and side portions, having a drive wheels driven by a drive unit for moving the robot cleaner along a floor surface. The robot cleaner also comprises a tilt axis determined by the points of contact between the drive wheels and the floor surface, a suction unit provided at a lower portion of the housing to suck dust and the like on the floor surface. The suction unit is provided near to the front portion. The robot cleaner also comprises an inclination adjustment unit configured to adjust an angle of inclination of the housing about the tilt axis in relation to the floor surface, a sensor unit placed on the upper portion which is configured to sense and mapping a surrounding space, a traveling control unit configured to control the drive unit, and an inclination control unit configured to control the inclination adjustment unit. The lower portion of the housing is provided with a supporting wheel which is in constant contact with the floor surface and which can be moved up and down relative to the housing by the inclination adjustment unit for adjusting the angle of inclination of the housing in relation to the floor surface. The supporting wheel is arranged between the tilt axis and the rear portion of the robot cleaner. The robot cleaner also comprises calculation unit with a memory for saving data, they can be integrated with other units of the robot cleaner, for instance with the traveling control unit or it can be separated unit, connected with others units of the robot cleaner to exchange and processing information and data. The drive unit and other unit of the robot cleaner are powered by a rechargeable battery that is integrated in the housing.

The objects of the present invention are solved also by the method for controlling the robot cleaner.

Because of changing the angle of inclination of the housing that is made by moving up, namely toward the housing or moving down, namely towards the floor surface the supporting wheel which has constant contact with the floor surface, it finally changes the height of the front portion what is helpful for the robot cleaner to overcome the obstacles. That is achieved by adjusting merely one simple for controlling the supporting wheel. The overcoming of the obstacles and simplification of the structure of the robot cleaner has been achieved.

In a preferred embodiment of the invention the supporting wheel is being connected to the inclination adjustment unit in such way that it can be rotated about two axes of rotation relative to the housing, a horizontal axis that is coaxial with a rotation axis of the supporting wheel and a vertical axis that is substantially perpendicular to the horizontal axis. The positive effect is that a rolling resistance of the robot cleaner is reduced, so it saves electric energy that is supplied by the battery. Preferably the vertical axis and horizontal axis do not intersect each other, then the wheel is self-adjusting wheel, it means that it self-aligns with the direction of travel of the robot cleaner along it a cleaning path, so that the resistance of the movement of the robot cleaner has been low to save energy.

In a preferred embodiment of the invention the down and up movement of the supporting wheel causing that the front portion of the housing has been moved up and down respectively, takes place along the vertical axis. The support wheel reciprocates along the vertical axis. Because drive wheels are arranged in the middle between the front and the rear portion of the housing, therefore the housing is capable to reach determined negative and positive the angle of inclination.

In another embodiment of the invention the sensor unit is a lidar sensor which rotates around its axis and produces a laser beam that is parallel to the upper surface and that is used for mapping the surrounding space. Lidar sensor is arranged above the supporting wheel near to the rear portion of the housing. The lidar sensor is rotated about its axis that is parallel to the vertical axis, so the laser beam is substantially parallel to the upper portion of the housing. The positive effect is that the laser beam generated by the lidar sensor changes inclination in relation to the floor surface which is caused by the movement of the supporting wheel along the vertical axis.

In another embodiment of the invention the angle of inclination can be positive or negative in relation to the horizontal position of the housing at which the angle of inclination equals zero, wherein the value of the angle of inclination depends on the position of the supporting wheel along the vertical axis which changes the angle of incidence of the laser beam

Preferable the sensor unit is arranged to get information to build 3d map of the cleaned room using the changes of the angle of incidence of a laser beam that is emitted by the sensor unit caused by the change of the angle of inclination of the housing.

Preferable sensor unit is configured to measure the height of the obstacles from the floor surface by changing the angle of incidence of a laser beam that is emitted by the sensor unit caused by the change of the angle of inclination of the housing caused by the inclination adjustment unit.

Preferable the previously built 3d map of the cleaned room that is saved in the memory, and the unit sensor which is utilized to measure the distance to the obstacles, and based on a measurement result, the inclination adjustment unit adjusts a front portion height and a front portion lower edge height at a predetermined distance in front of the obstacle.

Preferable a center of the gravity is disposed between the tilt axis and the rear portion of the housing in order to ensure constant contact the supporting wheel with the floor surface. The positive effect is that the supporting wheel is constantly pressed against the floor surface.

Preferable the suction unit is adapted to freely swing extend from or retract into the lower portion of the housing transversally to a cleaning path. Therefore a close distance between the suction input and the floor surface is ensured, which is essential for high cleaning efficiency, indecently from the angle of inclination of the housing.

A method for controlling the robot cleaner includes step of: beginning of cleaning job the robot cleaner starts to execute cleaning mission, the angle of inclination of the housing relate to the surface floor equals zero, then the supporting wheel moves up and down regularly which changes the angle of incidence of a laser beam provided for mapping surroundings because the supporting wheel is in constant contact with the surface floor, it causes that height values of the surrounding things are integrated into environment map. It is built 3d map of the cleaned room, it means that map contains information about the room layout, and it also contains information about the height of the obstacles. In the another step the robot cleaner analyzes environment map for nearby surrounding, if the robot cleaner encounters obstacles. Analyzes the possibility of overcoming it depending on its type and takes predetermined action using the possibility that the inclination angle of the housing can be changed in the broad scope from negative to positive value of the angle of inclination, so the height of the front portion of the housing can be adjusted, then continue execution of cleaning mission.

The method may comprises the further steps, when an obstacle as a cliff on the planned cleaning path is detected in close proximity, then the supporting wheel is moved down in several steps and turning of the robot cleaner to scan the cliff with more detail by the laser beam, the angle of inclination becomes negative, the laser beam shines closer the robot cleaner, then circumvent the cliff, moving the supporting wheel to standard position when the angle of inclination of the housing equals zero, then continue execution of cleaning mission.

In another embodiment the method comprises further steps, when an obstacle as a doorsill on the planned cleaning path is detected in close proximity, then the supporting wheel is moved down in several steps and turning of the robot cleaner to scan the doorsill with more detail by the laser beam, the angle of inclination becomes negative, then approaching the doorsill, then the supporting wheel is moved up the angle of inclination becomes positive, a front portion lower edge is over the doorsill, then overcome the doorsill with robot cleaner moving the supporting wheel to standard position when the angle of inclination of the housing equals zero, then continue execution of cleaning mission.

In another embodiment the method comprises further steps, when an obstacle as a furniture with a recess that allows to drive partly under it detected in close proximity, then moving down and/or moving up of the supporting wheel in several steps and turning of the robot cleaner to scan the recess of the furniture with more detail by the laser beam, approaching the obstacle, moving down of the supporting wheel to the smallest height of the front portion, the angle of inclination becomes negative, drive under furniture up to the stop, drive backwards and restart same maneuver with lateral shift until complete the recess is cleaned, moving the supporting wheel to standard position when the angle of inclination of the housing equals zero, then continue execution of cleaning mission.

In another embodiment the method comprises further steps, when the obstacle for the sensor unit that protrudes from the upper portion on the planned cleaning path is detected in close proximity, then the supporting wheel is moved up of in several steps and turning of the robot cleaner to scan the obstacle with more detail by the laser beam, the angle of inclination becomes positive, circumvent the obstacle, moving down the supporting wheel to standard position when the angle of inclination of the housing equals zero, then continue execution of cleaning mission.

Further benefits and advantages of embodiments of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.

Fig. 1 is a perspective view of the upper portion of a robot cleaner in accordance with a preferred embodiment of the present invention.

Fig. 2 is a perspective lower portion view of a robot cleaner in accordance with a preferred embodiment of the present invention.

Fig. 3 is a side plan view of a robot cleaner in accordance with a preferred embodiment of the present invention, when the angle of inclination equals zero

Fig. 4 is a side plan view of a robot cleaner in accordance with a preferred embodiment of the present invention, when the angle of inclination is positive.

Fig. 5 is a side plan view of a robot cleaner in accordance with a preferred embodiment of the present invention, when the angle of inclination is negative.

Fig. 6 is a top side view of robot cleaner moving along a possible cleaning path, when the recess e.g. under the furniture is cleaned.

Fig. 7 presents the algorithm of the cleaning procedure. Referring to the drawings and initially to Figs. 1-6, a robot cleaner 1 in accordance with the preferred embodiment of the present invention comprises a housing 2 having a flat rectangular shape with rounded corners. The housing 2 has a lower portion 18 facing towards a floor surface 13, an upper portion 19, a front portion 3 facing toward a forward direction of the robot cleaner 1, a rear portion 4 and side portions, two drive wheels 7 arranged in the middle between the front portion 3 and the rear portion 4. Wheels 7 are driven by a drive unit (not shown) for moving the robot cleaner 1 along the floor surface 13 in the determined direction along an cleaning path 17. The robot vacuum cleaner 1 changes the direction of movement in the base of the speed differential between the wheels 7. Points of contact between the drive wheels 7 and the floor surface 13 determine a tilt axis 10 of the housing 2. The housing 2 has a suction unit 8 provided at a lower portion 18 to suck dust and the like on the floor surface 13, arranged near to the front portion 3 in order to clean space close to wall or obstacle. The suction 8 unit comprises a brush roller 9 to efficiently pick up the dust. The suction unit 8 is adapted to freely swing, about an axis transversal to a cleaning path 17, so can extend from or retracts into the lower portion 18 of the housing 2, therefore a close distance between the suction unit 8 and the floor surface 13 is ensured independently from the angle of inclination a of the housing 2, which is essential for high cleaning efficiency.

The housing 2 has an inclination adjustment unit (not shown) configured to adjust the angle of inclination a of the housing 2 about the tilt axis 10 in relation to the floor surface 13, and a lidar sensor 5 placed on the upper portion 19, that protrudes from the upper portion 19 to sense and mapping a surrounding space. Furtherly the housing 2 has a traveling control unit (not shown) configured to control the drive unit, and an inclination control unit (not shown) configured to control the inclination adjustment unit, The lower portion 18 of the housing 2 is provided with a supporting wheel 6 which is in constant contact with the floor surface 13 and which can be moved up and down relative to the housing 2 by the inclination adjustment unit for adjusting the angle of inclination a of the housing 2 in relation to the floor surface 13. The supporting wheel 6 is arranged on the lower portion 18, between the tilt axis 10 and the rear portion 4 of the robot cleaner 1. In order to ensure the constant contact of the supporting wheel 7 with the floor surface 13, the robot cleaner 1 is arranged in that way that it’s a center of the gravity is disposed in the middle between the tilt axis 10 and the rear portion 4 of the housing 2. The supporting wheel 6 is being connected to the inclination adjustment unit in such way that it is rotated about two axes of rotation relative to the housing 2, namely a horizontal axis 21 that is coaxial with a rotation axis of the supporting wheel 6 and a vertical axis 20 that is substantially perpendicular to the horizontal axis 21 and they do not intersect each other. So, the supporting wheel 6 is a self-adjusted caster wheel 6, that is shown in Figs.2-5. The down and up movement of the caster wheel 6 which takes place along the vertical axis 20, causes that the front portion 3 of the housing 2 respectively has been moved down and up, as shown in Figs.3-5.

The robot cleaner 1 comprises the lidar sensor 5 which rotates around its axis and produces a laser beam 12 that is parallel to the upper surface 19 and that is used for mapping the surrounding space and that is arranged above the caster wheel 6 near to the rear portion 4 of the housing 2. In relation to the vertical position of the caster wheel 6, the angle of inclination a can be positive a+ or negative a- in relation to the horizontal position of the housing 2 at which the angle of inclination a=0. The lidar sensor 5 is arranged to get information to build 3d map of the cleaned room using the changes the angle of incidence of a laser beam 12 that is emitted by the lidar sensor 5 caused by the change of the angle of inclination a of the housing 2. The lidar sensor 5 is configured to measure the height of the obstacles 14, 16 from the floor surface 13 level by changing the angle of incidence of a laser beam 12 caused by the change of the angle of inclination a of the housing 2 done by the inclination adjustment unit.

Previously built 3d map of the cleaned room and the measurement result of the lidar sensor 5 which is arranged to measure the distance to the obstacles 14, 16, are the basis for determination a front portion height A and a front portion lower edge height B at a predetermined distance in front of the obstacle 14,16 by the inclination adjustment unit. The robot cleaner 1 also comprises a calculation unit with a memory for saving data (not shown), connected with others units of the robot cleaner 1 to exchange and processing information and data. The drive unit and other unit of the robot cleaner are powered by a rechargeable battery that is integrated in the housing.

Fig.7 shows the robot cleaner 1 cleaning procedure algorithm. When the robot cleaner 1 starts to execute cleaning mission, at the beginning the angle of inclination a of the housing 2 equals zero, the caster wheel is in a standard position, then the caster wheel 6 moves up and down regularly along the vertical axis, it changes the angle of incidence of a laser beam 12 provided for mapping surroundings. Height values of things placed in the room are integrated into environment map, so it is built 3d map of the cleaned room, the robot cleaner analyzes environment map for nearby surrounding, If the robot cleaner 1 encounters an obstacles e.g. furniture 14, a doorsill 16 a cliff 22, analyzes the possibility of overcoming it depending on its type and takes predetermined action, then continue execution of cleaning mission. When an obstacle as the cliff 22 on the planned cleaning path 17 is detected in close proximity, then the caster wheel 6 is moved down in several steps and turning of the robot cleaner 1 to scan the cliff 22 with more detail by the laser beam 12, then the angle of inclination a becomes negative a-, then circumvent the cliff 22, moving up the caster wheel 6 to standard position when the angle of inclination a of the housing 2 equals zero, then continue execution of cleaning mission. When an obstacle as the doorsill 16 on the planned cleaning path 17 is detected in close proximity, then the caster wheel 6 is moved down in several steps and turning of the robot cleaner 1 to scan the doorsill 16 with more detail by the laser beam 12, then the angle of inclination a becomes negative a-, then approaching the doorsill 16, the caster wheel 6 is moved up, the angle of inclination a becomes positive a+, a front portion lower edge 11 is over the doorsill 16, i.e. the front portion lower edge height B is greater than the doorsill height Y, then the robot cleaner 1 overcomes the doorsill 16, moving down the caster wheel 6 to standard position when the angle of inclination a of the housing 2 equals zero, continue execution of cleaning mission. When an obstacle as a furniture 14 with a recess 15 of height X that allows to drive partly under it detected in close proximity, then the caster wheel 6 is being moved down and/or moved up in several steps and turning of the robot cleaner 1 to scan the recess 15 of the furniture 14 with more detail by the laser beam 12, then approaching the furniture 14, moving down of the caster wheel 6 to the smallest height of the front portion A, the angle of inclination a becomes negative a-, when the height of the front portion A is smaller than the recess height X, then the robot cleaner 1 drives under furniture 14 up to the stop, drives backwards and restart same maneuver with lateral shift until complete the recess 15 is cleaned, then moving up the caster wheel 6 to standard position when the angle of inclination a of the housing 2 equals zero and continue execution of cleaning mission. When the obstacle for the lidar sensor 5 that protrudes vertically from the upper portion 19 on the planned cleaning path 17 is detected in close proximity, then the caster wheel 6 is being moved up in several steps and turning of the robot cleaner 1 to scan the obstacle with more detail by the laser beam 12, then the angle of inclination a becomes positive a+, then circumvent the obstacle, moving down the caster wheel 6 to standard position when the angle of inclination a of the housing 2 equals zero, and continue execution of cleaning mission. List of the reference signs

1 robot cleaner

2 housing

3 front portion

4 rear portion

5 sensor unit

6 supporting wheel

7 drive wheel

8 suction unit

9 roller brush

10 tilt axis

11 front portion lower edge

12 laser beam

13 floor surface

14, 16, 22 obstacle

14 furniture

15 recess

16 doorsill

17 cleaning path

18 lower portion

19 upper portion

20 vertical axis

21 horizontal axis

22 cliff

A front portion height

B front portion lower edge height

X recess height

Y doorsill height a angle of inclination