Control device for a mobile robot

Abstract

Control device (100) for a mobile robot (105), the control device (100) comprising: - a plurality of light sources (125) for emitting light in a predetermined section of an environment of the robot (105); - a light sensor (130) for detecting light for all included light sources (125); - optical fibers (135) for guiding emitted light, which has been reflected by an object (115) in the environment of the robot (105), from a predetermined receiving position (145) on the robot (105) to the light sensor (130), wherein each light source (125) is associated with an optical fiber (135) which is designed to guide only light to the light sensor (130) which has been reflected in the section illuminated by the light source (125) associated with the fiber (135), and wherein all optical fibers (135) lead to the same light sensor (130); - means (160) for determining a distance of the object (115) from the receiving position (145) on the basis of the emitted and detected light; and - a processing device (165) for controlling the robot (105) over a floor (110) depending on the determined distance.

Description

[0001] The present invention relates to a control device for a mobile robot. In particular, the invention relates to the control of the robot as a function of a distance to an obstacle.

[0002] An automatic vacuum cleaner is designed to move across a floor in a predetermined area and clean it using a suction system. To prevent the automatic vacuum cleaner from damaging itself or an object, or injuring a person or pet, it can be equipped with various sensors to scan its surroundings. For example, US 2004 / 0 020 000 A1 describes an automatic cleaning robot with sensors.

[0003] Such a sensor includes a fall sensor to ensure that the automatic vacuum cleaner does not suffer damage from a fall, for example, when driving over the top of a staircase or sideways off the edge of a gallery. The fall sensor is attached to the underside of the vacuum cleaner and determines the distance to the floor. The determination is usually made contactlessly using light. Different measurement principles are based, for example, on triangulation or the speed of propagation of light (time of flight, ToF). In this case, light is usually emitted, reflected off the ground, and received again. If the distance between the sensor and an object reflecting the light exceeds a predetermined threshold, the vacuum cleaner can be stopped.

[0004] The paper "Focus-Induced Photoresponse: a novel optoelectronic distance measurement technique" by Oili Pekkola et al. (Cornell University arXiv.org) describes the principle of focus-induced photoresponse for distance measurement.

[0005] Such sensors can represent significant cost factors for the automatic vacuum cleaner. Due to their location and small size, they can be exposed to significant contamination, which can interfere with or prevent distance determination. It has been suggested that an optical fall sensor be placed in a separate housing that is easier to clean. However, the housing and its installation may incur additional costs for materials or assembly.

[0006] An object underlying the present invention is to provide an improved control device for a mobile robot as a function of a specific distance from an object in its surroundings. The invention solves this problem by means of the subject matter of the independent claims. Subclaims specify preferred embodiments.

[0007] According to a first aspect of the present invention, a control device for a mobile robot comprises a plurality of light sources for emitting light in a predetermined section of the robot's environment; a light sensor for detecting light for all of the included light sources (125); optical fibers for guiding emitted light, which has been reflected by an object in the robot's environment, from a predetermined receiving position on the robot to the light sensor, wherein each light source (125) is associated with an optical fiber (135) configured to guide only light to the light sensor (130) that has been reflected in the section illuminated by the light source (125) associated with the fiber (135), and wherein all of the optical fibers (135) lead to the same light sensor (130); means for determining a distance of the object from the receiving position based on the emitted and detected light;and a processing device for controlling the robot over a floor depending on the determined distance;

[0008] By using optical fibers between the receiving position and the light sensor, the latter can be better protected against contamination, abrasion, or collision. The light sensor can be mounted in a protected location inside the mobile robot, and the optical fiber can be easily routed from there to the receiving position. One end of the fiber, where light can enter, can be easily attached to the mobile robot, making it easier to select the receiving position.

[0009] It is particularly preferred that the distance be determined based on the focus-induced photoresponse (FIP). A corresponding sensor for FIP-based distance measurement using an optical fiber is available under the name "trinamiX fiber optic sensor." The underlying measuring principle is described in more detail in WO 2012 / 110 924 A1, for example. Such a determination may require neither triangulation nor a time-of-flight measurement of light. The measurement can be robust to the color of a background, the light intensity used, or contamination of the optical path. Distances in the range of approximately 0 to approximately 150 millimeters can be determined reliably and with high precision.

[0010] In one embodiment, the light source can be located directly at an exit position on the robot. In another embodiment, the control device comprises an additional optical fiber for guiding light emitted by the light source to the predetermined exit position on the robot. This also allows the light source to be mounted in a protected location inside the robot. The light source can be arranged in the area of ​​the light sensor, allowing for improved integration of optoelectronic components.

[0011] The exit position and the receiving position are preferably located close to one another on the robot. For this purpose, a holding element can be provided which is designed to attach ends of the fibers to the robot such that the exit position is at a predetermined distance from the receiving position. The holding element can comprise exclusively optical elements and can be handled and attached to the robot according to optical or mechanical aspects. The determination of the distance to the object cannot be impaired by deformation of the fibers or by electromagnetic influences on the fibers or in the region of the holding element. The predetermined distance is preferably in a range between a few millimeters and approximately one centimeter. In a further embodiment, the holding element can also accommodate the light source instead of the end of the further fiber.

[0012] According to the invention, the control device is configured to determine multiple distances to objects in the area of ​​the robot. For this purpose, the control device comprises multiple light sources, each light source configured to illuminate a predetermined section of the environment. Each light source is assigned an optical fiber configured to guide only light reflected in the section illuminated by the light source assigned to the fiber to the light sensor. In this way, distances to objects in the multiple sections are determined using only one light sensor. The light sources can be activated sequentially to perform only one distance measurement in one of the sections at any one time. The sections are preferably non-overlapping (disjoint), so that light from a first light source cannot be reflected by an object and penetrate an optical fiber assigned to another light source.

[0013] In particular, it is preferred that the sections lie in different spatial directions with respect to the robot. This allows different measuring directions to be formed, each of which can lie between the robot and the object. More precisely, a measuring direction can extend between a first location on the robot, at which the exit position and the receiving position are located, and a second location on the object where the light is reflected. The spatial directions can comprise a Cartesian coordinate system, in particular a right-hand system, with respect to the vehicle axes of the robot. The vehicle axes can in particular comprise a longitudinal axis, a transverse axis, and a vertical axis. Measuring directions of different sections can enclose an angle of approximately 90° with one another.

[0014] Preferably, a first measuring direction runs horizontally and a second vertically relative to the robot. Particularly when an exit position and an associated receiving position are close to each other, the emitted and reflected light can propagate in a relatively narrow corridor, making interference by external light unlikely. To focus the emitted light, the light source can comprise a light-emitting diode or a laser. Focusing optics, such as a collimator, can be provided in the area of ​​the exit position and / or the receiving position.

[0015] It is particularly preferred that a first section is offset horizontally and a second section is offset vertically relative to the robot. A side section, in particular the first, horizontally offset section, can be located next to the robot, wherein the processing device is configured to control the robot across the floor in such a way that a predetermined distance from an object in the side section is maintained. If the object comprises, for example, an elongated object such as a wall, the robot can be moved along the wall at a predetermined distance. The measuring unit can thus operate as a wall-following sensor.

[0016] A floor section, in particular a second section offset vertically relative to the robot, can be located below the robot, wherein the processing device is configured to steer the robot across the floor in such a way that crossing a step or threshold in the floor section is avoided. In particular, if the step or threshold exceeds a predetermined amount in terms of magnitude or gradient, a movement of the robot can be modified to prevent a fall or getting stuck. In particular, the robot can be stopped and, if necessary, brought to safety in the opposite direction.

[0017] According to a second aspect of the present invention, a robot comprises a control device as described herein.

[0018] The robot can in particular comprise a household appliance. In particular, the robot can be configured to travel autonomously over the floor and have a device for working the floor. Such a floor processing device can, for example, comprise a wiping device, a sweeping device, a vacuuming device, or a cutting unit. The household appliance can, for example, comprise a cleaning robot or an automatic lawnmower. The processing device is preferably configured to guide the robot over the floor in a predetermined manner in order to work it using the floor processing device. The robot is usually configured to travel over the floor in a predetermined manner in order to work at least predetermined areas as comprehensively as possible.

[0019] The invention will now be described in more detail with reference to the accompanying figures, in which: Fig. 1 a control device for a mobile robot; and Fig. 2 shows a mobile robot with a control device.

[0020] Fig. 1 shows a schematic representation of an exemplary control device 100 for a mobile robot 105. The robot 105 preferably comprises a household appliance, in particular a floor-cleaning robot such as a vacuum robot. The control device 100 is preferably configured to control a movement of the robot 105 across a floor 110 as a function of a distance from an object 115. Furthermore, the control device 100 can control a function of the robot 105, in particular a processing of the floor 110.

[0021] The control device 100 comprises one or more measuring units 120, by means of which independent distance measurements, for example to an object 115, can be carried out. A Fig. The measuring unit 120 shown in more detail in Figure 1 preferably comprises a light source 125, a light sensor 130, a first optical fiber 135 for guiding light to the light sensor 130, and a second optical fiber 140 for guiding light from the light source 125. The first optical fiber 135 receives light from a receiving position 145, which is preferably located in the region of an outer skin of the robot 105. The second optical fiber 140 emits light at an exit position 150 on the robot 105. The receiving position 145 and the exit position 150 are preferably located close to one another. A holding element 155 can be provided for fixing ends of the fibers 135, 140 and for maintaining a predetermined distance, a predetermined orientation, or for receiving an optical element.

[0022] A distance of the object 115 from the positions 145, 150 on the holding element 155 is preferably determined using the principle of focus-induced photoreaction. A surface of the object 115 can be illuminated by the light source 125. The light sensor 130 can comprise two individual sensors that have different focal lengths with respect to an imaging optics, in particular a collimator lens. Depending on the distance of the object 115, a light spot projected onto the sensors can be detected by them as having different brightnesses. The distance to the object 115 can be determined based on a ratio of brightnesses determined by the sensors.

[0023] In a further embodiment, a light source 125 is provided on the holding element 155 or at the exit position 150 of a measuring unit 120. In this embodiment, the second optical fiber 140 can be omitted; instead, an electrical line can be provided to provide energy to the light source 125.

[0024] In the embodiment according to the invention, further measuring units 120 are provided by way of example. Currently available measuring systems can support up to five measuring units 120. Each measuring unit 120 can be assigned a light source 125, a first optical fiber 135, a second optical fiber 140, and a holding element 155. However, only one light sensor 130 is provided for all of the measuring units 120 included. First optical fibers 135 of the individual measuring units 120 all lead to the same light sensor 130. To perform a measurement, preferably only one of the light sources 125, which is assigned to the desired measuring unit 120, is activated at any given time. The measuring units 120 are preferably configured or aligned on the robot 105 in such a way that their beam paths do not overlap one another as far as possible in the environment of the robot 105.In another embodiment, measurements with different measuring units 120 can also be differentiated from one another in other ways, for example by modulating the emitted light of the individual measuring units 120 in different ways and determining a measurement signal with the desired modulation at the light sensor 130. For example, the light sources 125 can use different light spectra or be modulated with different modulation frequencies.

[0025] The individual distances can be determined by means of a device 160, which in one embodiment can also comprise optoelectronic components such as the light sources 125 or the light sensor 130. In addition, a processing device 165 can be provided to control the robot 105 depending on one or more specific distances. The processing device 165 can be connected via an interface 170 to a drive system, a steering system, and / or another scanning system for an environment of the robot 105. Optionally, the processing device 165 comprises a map memory for storing map data that describe an environment of the robot 105. Map data can be generated based on information from the scanning system or compared with existing map data.

[0026] Fig. 2 shows two views of a mobile robot 105 with a control device 100. In an upper area of Fig.2, the robot 105 is shown from below; in a lower section, from the front. For easier referencing, coordinate systems are shown, with an x-axis corresponding to a longitudinal axis of the robot 105 in the direction of travel, a z-axis perpendicular to the floor 110, and a y-axis correspondingly completing a right-hand system.

[0027] To control and guide the robot 105 across the ground 110, a chassis is provided, which in the illustrated embodiment comprises, for example, two drive wheels 205 and an unsteered nose wheel 210. The drive wheels 205 can be controlled independently of one another in terms of direction and speed in order to steer, rotate, accelerate, or decelerate the robot 105. For cultivating the ground 110, a soil cultivating device 215 is preferably provided, which, for example, is located essentially between the drive wheels 205 here.

[0028] In the illustrated embodiment, five measuring units 120 are provided, each configured to detect an object 115 in a designated, assigned measuring direction. Three of the measuring units 120 have vertical measuring directions and are directed downwards, so that they can each determine a distance along the z-axis to the floor 110. Based on these distance measurements, it can be determined when the robot 105 is about to cross a step, posing a risk of falling. Two further measuring units 120 are oriented horizontally, so that their measuring directions run at least partially along the y-axis. With these measuring units 120, a distance to an object 115 can be determined. If the object 115 is elongated, the robot 105 can be moved along the object 115 so that a distance to the object 115 does not fall below a predetermined threshold.The object 115 can in particular comprise a wall or a piece of furniture. Reference symbol 100 control device 105 robots 110 Floor 115 objects 120 measuring units 125 light source 130 light sensor 135 first optical fiber 140 second optical fiber 145 Reception position 150 Exit position 155 Holding element 160 Device for determining the distance 165 processing facility 170 interface 205 drive wheel 210 nose wheel 215 Soil cultivation device

Claims

[1] Control device (100) for a mobile robot (105), the control device (100) comprising: - a plurality of light sources (125) for emitting light in a predetermined section of an environment of the robot (105); - a light sensor (130) for detecting light for all included light sources (125); - optical fibers (135) for guiding emitted light, which has been reflected by an object (115) in the environment of the robot (105), from a predetermined receiving position (145) on the robot (105) to the light sensor (130), wherein each light source (125) is associated with an optical fiber (135) which is designed to guide only light to the light sensor (130) which has been reflected in the section illuminated by the light source (125) associated with the fiber (135), and wherein all optical fibers (135) lead to the same light sensor (130); - means (160) for determining a distance of the object (115) from the receiving position (145) on the basis of the emitted and detected light; and - a processing device (165) for controlling the robot (105) over a floor (110) depending on the determined distance. [2] The control device (100) of claim 1, wherein the distance of the object (115) is determined based on the focus-induced photoresponse. [3] Control device (100) according to claim 1 or 2, further comprising another optical fiber (140) for guiding light emitted from the light source (125) to a predetermined exit position (150) on the robot (105). [4] Control device (100) according to claim 3, further comprising a holding element (155) for attaching ends of the fibers (135, 140) to the robot (105) such that the exit position (150) is at a predetermined distance from the receiving position (145). [5] Control device (100) according to one of the preceding claims, wherein the sections lie in different spatial directions with respect to the robot (105). [6] Control device (100) according to one of the preceding claims, wherein a first section is offset horizontally and a second section is offset vertically with respect to the robot (105). [7] Control device (100) according to one of the preceding claims, wherein a side section is located next to the robot (105), wherein the processing device (165) is configured to control the robot (105) over the floor (110) in such a way that a predetermined distance from an object (115) in the side section is maintained. [8] Control device (100) according to one of the preceding claims, wherein a floor section (110) lies below the robot (105), wherein the processing device (165) is adapted to control the robot (105) over the floor (110) in such a way that driving over a step or threshold in the floor section (110) is avoided. [9] Robot (105) comprising a control device (100) according to one of the preceding claims. [10] Robot (105) according to claim 9, further comprising a device (215) for processing the floor (110).

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