DE102021207324A1 - Drive unit for a ground robot - Google Patents

Abstract

A drive unit for a ground robot, the drive unit comprising: a first wheel; a second wheel; a traction device that runs over both wheels; an elastic member for pressing down the first wheel with respect to the floor robot; and an actuator for controlling a prestress of the elastic element.

Description

The present invention relates to a drive unit for a floor robot. In particular, the invention relates to a drive unit for a cleaning robot in a household.

A vacuum cleaning robot is set up to move autonomously over a floor area and to clean it. For this purpose, the vacuum cleaning robot includes a suction device and a drive device. A control device is set up to scan an area surrounding the robot vacuum cleaner using a number of sensors and to control the robot vacuum cleaner on the floor surface. The vacuum cleaning robot can be used in particular in a household.

Different floor coverings, objects lying on the floor such as carpets, cables or pieces of furniture, or structural conditions such as doorsteps or uneven sections can place great demands on the flexibility of the drive device. The drive device usually includes two drive wheels, which can each be driven by means of an associated electric motor. The drive wheels are attached to the right and left of the robot vacuum cleaner, with support wheels being able to be provided in front of and behind the drive wheels. Each drive wheel can preferably be individually springed out of the device, so that contact with the ground can be maintained if the device hits an obstacle with a front or rear edge.

In order to better overcome an obstacle, it was proposed to equip the ground robot with a chain drive. This includes a front and a rear sprocket, over which a chain runs, which is usually made of a plastic. Compared to a drive wheel, traction of the chain drive can be improved by the enlarged usable bearing surface on the ground. However, good traction alone may not be enough to effectively overcome all obstacles encountered in a household. In particular, a vertical movement of the two wheels when overcoming an obstacle can be difficult to coordinate with one another or not go well with all obstacles. In certain situations, a known chain drive can even be disadvantageous for overcoming an obstacle.

It is an object of the present invention to provide an improved drive unit for a ground robot. The invention solves this problem by means of the subject matter of the independent claims. Subclaims reflect preferred embodiments.

According to a first aspect of the present invention, a driving unit for a floor robot includes a first wheel; a second wheel; a traction device that runs over both wheels; an elastic member for pressing down the first wheel with respect to the floor robot; and an actuator for controlling a prestress of the elastic element. The first wheel can be vertically movable with respect to the ground robot, while the second wheel can be rigidly attached.

According to the invention, a front part of the floor robot can be lifted off the ground or brought closer to it by increasing or reducing the prestressing of the elastic element. A rear part can be lowered onto the ground or lifted off it in a corresponding manner. In this way, the floor robot can be tilted forwards or backwards around the axis of rotation of the drive unit.

This makes it easier to climb up a vertical elevation or drive into a depression in a controlled manner. The ground robot can have one or more support wheels, which are attached in front of or behind the pivot axis. The floor robot can be controlled in such a way that it climbs a step up or down, for example.

In addition, the height of a processing device attached to the floor robot can be adjusted above a subsurface that is traveled over. If the processing device includes a suction device, for example, a suction mouth attached to the floor robot in front of or behind the axis of rotation can be moved to a predetermined height in order to prevent suction on the ground and at the same time to ensure efficient suction of dirt.

For normal operation, the elastic element is usually prestressed in such a way that the floor robot assumes a predetermined angle with respect to a level, flat surface. Normal operation may include driving across a horizontal surface, preferably a level surface. The elastic element is preferably partially compressed so that it can both contract and relax due to a vertical movement with respect to the ground robot of the first wheel.

It is preferred that the actuator includes a self-locking gear. This can prevent the actuator from absorbing energy while it does not have to adjust a predetermined position of the elastic element, but only has to hold it. The self-locking gear is preferably designed as a reduction gear to an Actuate to increase the tension force on the elastic element. The actuator can in particular include an electric motor.

In a preferred embodiment, the actuator comprises a cam disk. The elastic element can act between the first wheel and the floor robot. The cam disk is preferably attached to the floor robot in such a way that an end of the elastic element assigned to the floor robot can be moved closer to or away from the floor robot by turning the cam disk. The end can in particular be moved vertically downwards in order to increase the spring tension of the elastic element. The cam disc can comprise, for example, an eccentric circular disc or a disc with a contour that has the shape of a spiral in some sections.

In another preferred embodiment, the actuator includes a spindle drive. The spindle drive, also known as the threaded spindle, includes a threaded rod and a spindle nut. The spindle nut can be linearly adjusted by turning the threaded rod. In one embodiment, the threaded spindle is attached rigidly in relation to the floor robot and an end of the elastic element assigned to the floor robot is fastened to the spindle nut. The end of the elastic element can be moved in a straight line in a simplified manner by means of the spindle drive. In this case, a stepping down of the rotational movement into the linear movement can already be implemented.

In yet another embodiment, the actuator is set up to control a spring rate of the elastic element. When the spring rate is increased, a force required to compress the elastic member by a predetermined amount can be increased. Conversely, lowering the spring rate can increase this amount. The spring effect of the elastic element can thus be better adapted to different height settings of the first wheel. Punching through, ie complete compression of the elastic element, can be prevented in an improved manner.

In a further preferred embodiment, the drive unit includes a control device for controlling the actuator as a function of an obstacle to be overcome by means of the drive unit. The obstacle can in particular comprise an unevenness in the subsoil running vertically upwards or downwards. The control device can be set up to adapt the prestressing of the elastic element when driving over the unevenness in such a way that the floor robot climbs over the unevenness in an improved manner.

In a further preferred embodiment, the drive unit additionally includes a sensor for scanning an area surrounding the floor robot, the control device being set up to detect an obstacle to be overcome on the basis of a scan of the sensor. As a result, the drive unit can independently control a movement of the floor robot independently of an obstacle to be overcome in an improved manner. One or more sensors can be used to control the drive unit, which can be provided for detecting obstacles and/or orienting the floor robot in a predetermined environment.

A drive motor is preferably provided for driving the second wheel and the first wheel is in front of the second wheel with respect to a normal direction of travel of the floor robot. As a result, one strand of the traction mechanism can rest on the ground or be pressed against it. The strand of the traction means lying on the ground can be a load strand.

It is further preferred that the wheels have the same diameter. The ability of the drive unit to negotiate an obstacle can be good for either forward or reverse direction of travel. The drive unit can be simple and compact. A number of identical parts can be increased. Due to the same radii, the traction means can be subjected to less bending stress, so that its reliability or service life can be increased.

The traction mechanism formed from the first wheel, the second wheel and the traction means can be designed in particular as a chain drive with a first chain wheel, a second chain wheel and a chain. The chain is preferably articulated and can be made from a plastic. A form fit can be established between the chain and the sprockets in the direction of rotation. In another embodiment, the adhesion in the circumferential direction can be produced by frictional force; in this case one can speak of a belt drive. Due to the chosen construction, a distance between the two wheels can be independent of a movement of the first wheel around the second. A tension of the traction means can therefore be kept constant in an improved manner. A clamping mechanism may not be required.

If the traction mechanism is designed as a chain drive, a form fit between the traction mechanism and a wheel can be achieved by means of a depression and a projection engaging therein be effected. In this way, forces can be transmitted in the direction of rotation and/or perpendicular to it.

In particular when the traction means is constructed without a joint, the traction means can comprise a web pointing in the direction of the wheels, one of the wheels having a radial depression for receiving the web or a section thereof. In one embodiment, the web is circumferential and one of the wheels has a radial groove. The web on the traction means is usually located centrally with respect to an axis of rotation of one of the wheels. The web can also be eccentric, but it is preferred that the web is guided on both axial sides by the wheels. In a further embodiment, several webs can also be provided. The web can prevent the traction mechanism from slipping off one of the wheels in the axial direction. By dispensing with conventional, external axial thrust washers, the space required can be reduced.

In a further embodiment, the traction mechanism has a depression facing the wheels, and at least one of the wheels has a radial web for engaging in the depression. The web can be guided on the wheels in both axial directions. In particular, the web can be formed axially approximately centrally on the traction means. Several webs can also be provided, which are preferably each guided axially on both sides. A combination of this embodiment with the latter is also possible.

The elastic element can in particular comprise a compression spring. The compression spring can be accommodated compactly in the drive unit. Even if the compression spring breaks, an elastic residual effect can remain. Optionally, an arc spring can also be used in order to better cushion the first wheel on the circular arc. In alternative embodiments, a spiral spring or a torsion bar can also be used for the elastic mounting of the first wheel. In particular, the torsion bar can be attached longitudinally or transversely to the direction of travel of the drive unit.

According to a further aspect of the present invention, a first method for controlling a ground robot with a drive unit described herein, whose axis of rotation runs transversely to the direction of travel, comprises steps of detecting an obstacle to be overcome; tilting the ground robot around the axis of rotation depending on the obstacle; and driving the second wheel to overcome the obstacle.

The method can be used to efficiently overcome an obstacle. The obstacle can be positive or negative, with a positive obstacle being able to rise above ground on which the drive unit stands, while a negative obstacle being lowered relative to the ground. Before or while overcoming the obstacle, the floor robot can be tilted forwards or backwards about the axis of rotation relative to the ground. The tilting can be done in such a way that a force on a front or rear support wheel is specifically increased or decreased. The tilting can take place to such an extent that a front or rear end of the floor robot lifts off the ground, so that it can be slid onto or removed from the obstacle in an improved manner. After the obstacle has been overcome, the actuator can be controlled in order to bring the floor robot into a normal position about the axis of rotation with respect to a subsoil that is being driven on.

According to yet another aspect of the present invention, a second method for controlling a ground robot with a drive unit described herein comprises the steps of detecting a ground to be processed; and controlling a prestressing of the elastic element as a function of the detected subsoil in order to adjust a vertical distance of a processing device of the floor robot from the subsoil.

The processing device can be set up to carry out a method described herein in whole or in part. For this purpose, the processing device can comprise a programmable microcomputer or microcontroller and the method can be present in the form of a computer program product with program code means. The computer program product can also be stored on a computer-readable data carrier. Features or advantages of the method can be transferred to the device or vice versa.

• 1 einen Bodenroboter;
• 2 eine Antriebseinheit für einen Bodenroboter;
• 3 eine Antriebseinheit für einen Bodenroboter beim Überwinden eines Hindernisses;
• 4 eine Antriebseinheit für einen Bodenroboter in einer weiteren Ausführungsform; und
• 5 ein Ablaufdiagramm eines Verfahrens zum Steuern eines Bodenroboters mit einer Antriebseinheit

darstellt.The invention will now be described in more detail with reference to the accompanying figures, in which:

• 1 a ground robot;
• 2 a drive unit for a floor robot;
• 3 a drive unit for a ground robot when overcoming an obstacle;
• 4 a drive unit for a floor robot in another embodiment; and
• 5 a flow chart of a method for controlling a floor robot with a drive unit

represents.

1 shows an example of a ground robot 100. The ground robot 100 is set up to drive on and work on a subsurface. For this purpose, it includes a processing device 105, which includes a brush roller in the present example, and a drive device 110. The drive device 110 includes a left and a right ground wheel 115, which are attached to different sides of the ground robot 100 and can be driven independently of one another. Support wheels 120 can be attached in front of and behind the ground wheels 115 . If the ground robot 100 drives onto an elevation with its chassis or a support wheel 120, the ground wheels 115 can spring out automatically due to an elastic mounting. The drive device 110 is preferably attached to a base plate 125 of the floor robot 100 .

2 shows a drive unit 200 for a ground robot 100. The drive unit 200 stands, for example, on a level, flat base 205. The base plate 125 assumes a predetermined angle with respect to the base 205. A preferred direction of travel 210 is shown in FIG 2 from right to left. With regard to a coordinate system shown for reference, this corresponds to the negative x-direction. A y-direction extends vertically and a z-direction extends laterally. Coordinate systems in other figures facilitate a geometric assignment.

The drive unit 200 includes a traction drive 215, which includes a first wheel 220, a second wheel 225 and a traction mechanism 230. The traction mechanism 215 is preferably designed as a chain drive, with the traction mechanism 230 more preferably comprising a jointless chain, which can be designed in one piece and can more preferably be produced from a plastic. Gearing for mutual engagement and for the transmission of forces in the circumferential direction of the wheels 220, 225 can be provided between the traction means 230 and the wheels 220, 225. The toothing can also transmit forces in the transverse direction.

A holder 235 holds the wheels 220, 225 at a predetermined relative distance. The holder can be designed as a yoke, beam, rocker or spacer. The holder 235 is mounted so that it can rotate about an axis of rotation 240, about which the second wheel 225 can also rotate, as indicated by a double arrow. In another embodiment, the first wheel 220 may be vertically movably mounted in a different manner. The second wheel 225 is preferably mounted rigidly with respect to the floor robot 100 . The second wheel 225 can be driven about the axis of rotation 240 by means of a drive motor 245 . The holder 235 is prestressed about the axis of rotation 240 by means of an elastic element 250 in order to press the first wheel 220 about the axis of rotation 240 with respect to the floor robot 100 in the direction of the ground 205 . The elastic element 250 can comprise a metal spring, in particular a cylindrical spring and more preferably a compression spring.

For convenience of explanation, in the illustrated embodiment, the elastic member 250 is attached to a lever 255 connected to the holder 235, and the elastic member 250 acts in the horizontal direction. In another embodiment, the elastic element 250 can also be provided in the area of the first wheel 220 to save space. In particular, the elastic element 250 can act on an axle of the first wheel 220 . The elastic element 250 is mounted in relation to the floor robot 100 and can be supported in relation to a bearing block 260 which is connected to the floor plate 125 . A bearing that supports the holder 235 about the axis of rotation 240 may also be attached to the pedestal 260 .

More preferably, a stop 265 is provided to limit movement of the first wheel 220 . The stop 265 can define ends of the circular movement of the first wheel 220 about the axis of rotation 240 . In addition, the stop 265 can define the circular arc on which the axis of the first wheel 220 is guided around the axis of rotation 240 by the stop 265 determining a radial distance between the axis of the first wheel 220 and the axis of rotation 240 . The stop 265 can include a slotted guide, as in 2 is shown. An axle of the first wheel 220 or a guide pin connected to the holder 235 can be guided in a guide groove. The stop 265 can also be designed to be integrated with the bearing block 260 .

In a preferred embodiment, the elastic element 250 is attached in the area of the stop 265 and can press the first wheel 220 downwards. The elastic element 250 can be in the form of an arc spring or a compression spring which can be compressed until its coils abut one another. Since further compression of the elastic element 250 is then not possible, it can thus form a stop for a vertical movement of the first wheel 220 . The elastic element can be fitted in the guide groove of the slotted guide of the stop 265 .

The drive unit 200 can be designed as a separately manageable unit that can be built into the floor robot 100 by attaching the bearing block 260 to the latter.

It is particularly preferred that an actuator 270 is provided which is set up to pretension the elastic element 250 . For this purpose, the actuator 270 can be attached between the elastic element 250 and the bearing block 260 . In a preferred embodiment, the actuator 270 includes an electric motor with a self-locking gear, in particular a spindle drive. In a particularly preferred embodiment, actuator 270 includes a drivable cam disk for the vertical adjustment of an anchor point of elastic element 250 relative to floor robot 100.

In a variant, the actuator 270 can be set up to influence the spring characteristic of the elastic element 250 in addition to the pretension. To change the spring characteristic, an effective length of the elastic element 250 or the length of a lever via which it is articulated can be changed. For example, a horizontal leaf spring can be provided as the elastic element 250, the first end of which is connected to the floor robot 250 and the second end of which is connected to the first wheel 220 or its axis. The first end can be formed by a sliding bush pushed onto the leaf spring, which is movable in a rail on the base plate 205 and can thus be adjusted in its distance from the second end. By reducing the distance between the first and the second end, the spring characteristic can be changed by increasing a spring rate. In a further preferred embodiment, the preload and the spring characteristic can be changed simultaneously by means of only one actuator 270. In this case, an increase in the pretension is preferably associated with an increase in a spring constant and vice versa.

A control device 275 is also preferably provided, which is set up to activate the drive motor 245 and/or the actuator 270 in order to control a movement of the floor robot 100 . The control device 275 can be connected to a sensor 285 or another control device on board the ground robot 100 by means of an interface 280 . Interface 280 may include an electrical connector. The control device 275 can be set up to determine or receive an existing or intended driving state of the floor robot 100 and to control the drive unit 210 depending on the driving state.

The driving state can include a performed or intended movement of the ground robot 100 and/or an obstacle to be overcome. The control device 275 can scan an environment of the floor robot 100 using the sensor 285 and in particular determine a condition of the ground 205 . Exemplary sensors 285 include in particular a cliff sensor, a camera, a gyroscope, a rotation angle sensor for determining a rotation angle of the second wheel 225 or the holder 235, an inertial platform, a navigation sensor, for example based on a camera or a LiDAR sensor, a moment sensor, which determines a moment or a force on a shaft or a flange connection, an odometric sensor, a current sensor for determining an electric current flowing through the drive motor 245 or the actuator 270, an ultrasonic sensor and an infrared sensor.

3 12 shows an exemplary drive unit 200 overcoming an obstacle 305 in the exemplary form of a step. From top to bottom, the drive unit 200 is shown in three successive phases in overcoming the obstacle 305.

In an upper illustration, the obstacle 305 is in front of the drive unit 200 with respect to a travel direction 210. In a middle illustration, the first wheel 220 has started to climb onto the obstacle 305. The first wheel 220 is deflected upwards while the second wheel 225 remains on the ground 205 in front of the step. Lifting may be promoted by reducing a vertical force acting downward on the first wheel 220 using the actuator 270 .

In a lower illustration, the first wheel 220 has climbed the obstacle 305 and the second wheel 225 is still below the obstacle 305. At an upper edge of the obstacle 305, the traction mechanism 230 between the wheels 220, 225 is deflected. A downward bias on the first wheel 220 can now be increased by means of the actuator 270 and the second wheel 225 can be driven to move the floor robot 100 further in the direction of travel 210 until the second wheel 225 has also climbed the step. Subsequently, the preload acting on the first wheel 220 can be set back to an average value by means of the actuator 270, which can also apply in the illustration above.

4 shows a drive unit 200 for a floor robot 100 in a further embodiment. The drive unit 200 is shown attached to the base plate 125 of the floor robot 100, with the traction means 230 being detached from the wheels 220 and 225. In the present case, the actuator 270 comprises a cam disk 405 which can be rotated about an associated axis of rotation 410 . An electric motor, preferably with a downstream gearbox, can be used for the drive. the Distance of an outline of the cam disk 405 from the axis of rotation 410 in a predetermined direction of the actuator 270 depends on a rotational position of the cam disk 405 . For this purpose, the cam disk can comprise, for example, an eccentrically suspended circular disk, an ellipse or a disk with a spiral-shaped section.

Vertically below the axis of rotation 410 a guide pin 415 rests on the cam disk 405 . The elastic element 250 can act between the guide pin 415 and an axle of the first wheel 220 and is preferably designed as a cylinder spring, in particular as a compression spring. The guide pin 415 can be accommodated in the slotted guide of the stop 265 so that it can move vertically or on an arc of a circle.

A lower end of the elastic element 250 can act on the axis of the first wheel 220, and an upper end on the guide pin 415 and thus on the cam 405. In order to raise the base plate 125 relative to a base 205, the cam disk 405 can be rotated in such a way that the guide pin 415 is pressed radially downwards away from the axis of rotation 410. This movement is indicated by a curved arrow. If the cam disk 405 is rotated in reverse so that the guide pin 415 can be moved further vertically upwards with respect to the base plate 125, the height of the base plate 125 above a base 205 can thereby be reduced.

5 shows a flowchart of a method 500 for controlling a floor robot 100 with a drive unit 200. Two drive units 200 are preferably provided, which have a common axis of rotation 245 and are attached to the floor robot 100 in a laterally offset manner.

The method 500 can be carried out by means of a control device 275 which is set up to control a movement of a ground robot 100 . In addition, the control device 275 can control a functional function of the floor robot 100, in particular processing of a subsurface 205 by means of a processing device 105. In particular, an obstacle 305 in the area of the ground robot 100 can be determined on the basis of scanned information. The method 500 can be used to overcome the obstacle 305 with the ground robot 100 by controlling the drive unit 200 .

In a first step 505, the obstacle 305 to be overcome can be detected. In particular, it can be determined whether the obstacle 305 includes an elevation (positive obstacle 305) or a depression (negative obstacle 305) in the subsoil 205 . A multiple obstacle 305, for example in the form of a vertical or horizontal arrangement of elevations and/or depressions, can also be determined. The floor robot 100 can be brought into a position relative to the obstacle that allows the obstacle 305 to be driven over at an angle that is as obtuse as possible, in particular approximately 90°. In order to maneuver the floor robot 100, drive motors 245 of one or more existing drive units 200 can be actuated appropriately.

In a step 510 the ground robot 100 can be tilted about the axis of rotation 240 . At this time, the floor panel 125 can be raised at a front or rear end of the floor robot 100 . In order to tilt the floor robot 100, the actuator 270 can be controlled on a drive unit 200 in order to bias the first wheel 220 to a greater or lesser extent in the vertical direction. The actuator can be controlled until the floor robot 100 has reached a predetermined inclination. The inclination reached can be determined by means of a sensor.

In a step 515, the drive motor 245 can be controlled so that the second wheel 225 rotates about the axis of rotation 240 and exerts a traction force on the ground 205 via the traction mechanism 230 in order to move the floor robot 100 in the direction of the obstacle.

In a step 520 the obstacle 305 can be driven onto. If the obstacle 305 is positive, it can be determined that the first wheel 220 runs onto or climbs onto the obstacle. If the obstacle 305 is negative, it can be monitored how the first wheel 220 lowers into the obstacle 305 . To this end, it can be observed how far the first wheel 220 is deflected. The collision can be ended when the first wheel 220 has moved up or down as much as possible.

Optionally, the obstacle 305 can have a second edge, which can then be driven over in a corresponding manner. For example, an object to be driven over that is lying on a level surface can be interpreted as a sequence of a positive and a negative obstacle 305 .

After overcoming the obstacle 305, the ground robot 100 can be tilted back in a step 525 in order to assume a tilt provided for normal operation. In addition a previously raised end of the bottom plate 125 can be lowered again, or a previously lowered end can be raised. It should be noted that the raising and lowering of the floor panel 125 in steps 510 and 525 may also be controlled concomitantly with traversing the positive or negative obstacle 305 in step 520.

The method 500 can also be carried out in a slightly modified form for another purpose.

By controlling the bias of the elastic member 250, not only can the floor robot 100 be tilted, but also a vertical distance between a predetermined point on the floor robot 100 and the ground 205 can be increased or decreased. If a processing device 105 is provided on the floor robot, its vertical distance from the base 205 can be changed by changing the prestressing of the elastic element 250 . The method 500 can therefore also be used to support a function of the processing device 105 .

Thus, in step 505, a condition or a material of a subsurface 205 to be traveled over can be determined. In step 510, the vertical spacing of the processor 105 may be adjusted depending on the nature or material. For example, a smaller distance can be set on a smooth, hard surface 205 than on a soft surface or a long-pile carpet, so that it is possible to avoid sucking on the surface 205 .

In a further embodiment, the vertical height can also be adjusted based on another operating parameter of the ground robot 100 . For example, a power consumption of a suction unit can increase if a suction mouth comprised by the processing device 105 is sucked too hard onto the ground. The power consumption of the suction unit can be determined and the vertical height can be controlled depending on the determined power consumption.

The two variants of the method 500 can be integrated with one another, so that the height of the floor robot 100 above the ground 205 can also be adjusted with simultaneous adjustment due to an obstacle 305 to be overcome.

reference list

100

ground robot

105

processing facility

110

drive device

115

ground wheel

120

jockey wheel

125

bottom plate

200

drive unit

205

underground

210

driving direction

215

traction drive

220

first wheel

225

second wheel

230

traction means

235

holder

240

axis of rotation

245

drive motor

250

elastic element

255

lever

260

bearing block

265

attack

270

actuator

275

control device

280

interface

285

sensor

305

obstacle

405

cam disk

410

axis of rotation

415

guide pin

500

procedure

505

detect obstacle

510

lift the bottom plate

515

control the drive motor

520

drive over an obstacle

525

lower the floor plate

Claims (11)

Drive unit (200) for a ground robot (100), the drive unit (200) comprising: - a first wheel (220); - a second wheel (225); - A traction means (230) which runs over both wheels (220, 225); - an elastic element (250) around the first wheel (220) to push down on the ground robot (100); and - an actuator (270) for controlling a prestressing of the elastic element (250). Drive unit (200) after claim 1 , wherein the actuator (270) comprises a self-locking gear. Drive unit (200) after claim 2 wherein the actuator (270) comprises a cam (405). Drive unit (200) after claim 2 , wherein the actuator (270) comprises a spindle drive. Drive unit (200) according to one of the preceding claims, wherein the actuator (270) is set up to control a spring hardness of the elastic element (250). Drive unit (200) according to one of the preceding claims, further comprising a control device (275) for controlling the actuator (270) as a function of an obstacle (305) to be overcome by means of the drive unit (200). Drive unit (200) after claim 6 , further comprising a sensor (285) for scanning an environment of the ground robot (100); wherein the control device (275) is set up to detect an obstacle (305) to be overcome on the basis of a scan of the sensor (285). Drive unit (200) according to any one of the preceding claims; further comprising a drive motor (245) for driving the second wheel (225), the first wheel (220) being in front of the second wheel (225) with respect to a normal travel direction (210) of the floor robot (100). A power unit (200) according to any one of the preceding claims, wherein the wheels (220, 225) are of equal diameter. Method (500) for controlling a ground robot (100) with a drive unit (215) according to one of the preceding claims, wherein the axis of rotation (240) runs transversely to the direction of travel; the method (500) comprising the steps of: - detecting (505) an obstacle (305) to be overcome; - Inclining (510) of the ground robot (100) about the axis of rotation (240) depending on the obstacle (305); and - Driving (515) the second wheel (220) to overcome the obstacle (305). Method (500) for controlling a ground robot (100) with a drive unit (215) according to any one of the preceding claims; the method (500) comprising the steps of: - detecting (505) a subsurface (205) to be processed; and - Controlling (510) a prestressing of the elastic element (250) as a function of the detected subsurface (205) in order to adjust a vertical distance of a processing device (105) of the floor robot (100) from the subsurface (205).

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