KR20010041694A - Optical sensor system for detecting the position of an object - Google Patents

Abstract

The present invention relates to a particular light source for generating horizontal clowns. The clown is reflected by an object in the vicinity of the sensor system and transmitted to the photoelectric converter by a special imaging device. The imaging device is constructed in such a way that objects located at a distance appear to be a little further away, so that a better positional resolution of an object farther from the sensor system can be obtained over the entire imaging area from a general object with linear resolution. have. Preferably, a light emitting diode is provided on the optical axis of the cylindrical mirror as a light emitting element. The electrical signal emitted by the photoelectric converter is evaluated by the evaluation unit with respect to its position, and the evaluation unit uses triangulation to measure the distance of the object that reflected light.

Description

Optical sensor system for detecting object position {OPTICAL SENSOR SYSTEM FOR DETECTING THE POSITION OF AN OBJECT}

In the future, autonomous mobility systems in development and design will be seen more and more often in family life. The system will handle the transport and cleaning tasks at home and autonomously perform the tasks assigned to it with the help of a directional system. The orientation system allows the autonomous movement system to produce an image of the environment. In this case, the sensor system for detecting obstacles around the autonomous mobile unit is given important meaning along with different distance setting and evaluation algorithms. In order to induce consumer interest in autonomous mobile systems, it is very important to be able to manufacture them inexpensively and technically simply for a large number of components of the system. Therefore, the sensor system for detecting object position around the autonomous movement system must be durable and can be manufactured at low cost.

Optical sensor systems for performing object detection by triangulation are known in the prior art. A special measurement method is to perform active light triangulation with clown illumination. The main member of such a measurement system consists, for example, of a light source illuminating the vastness in space, an optical imaging system, a two-dimensional image receiver and an electronic device for processing and evaluation of signals received from the image receiver. To perform triangulation the system needs a light source that illuminates only the spatial vastness. An important feature of the light source is the surface density of the illumination output of the emitted light source. The power density of the light source must be large enough to recognize dark objects. Another feature of the light source is the thickness of the illuminated clown, which affects not only the detectable spatial area but also the resolution in measuring the position of the detected object.

At the present time the following possibilities for the embodiment of the light source for the provision of a light emitting band are known. That is, the fluorescent lamp or the fluorescent lamp using the radiation of the collimator objective lens through the collimator objective lens and the spherical mirror, and the cylindrical lens in front of the collimator objective lens to parallel the light of the laser source or the fluorescent lamp, the halogen lamp or the arc lamp There is a method of parallelizing the light emitted from the halogen lamps. The imaging system used in this case must in particular fulfill two main requirements. Firstly, the spatial area to be measured must be projected onto the surface of the two-dimensional image detector, and second, to ensure the desired position resolution in relation to the object to be measured. In this regard, position resolution means the minimum distance between objects that can be resolved upon imaging in a photoelectric converter. The distance is measured by the transducer used as with the imaging system. In this case, the objective of projecting a large spatial area at a wide angle in the form of a perfect half-space as possible, and achieving sufficient distance resolution using the same objective lens, is a contradictory condition. A possible means for enlarging the area of measurable space through the imaging system is to use a wide-angle objective lens that produces an image free of distortion. However, the objective lens having a plurality of lenses has a disadvantage in that it cannot project the full half space around it. Other objective lenses that project a full half-space on the other hand operate no longer distorted and are expensive to purchase. Distorted objectives also affect position resolution during triangulation. In this case, the in-plane distance between the images of the distracted light from two adjacent objects placed close to the imaging system is greater than that of two adjacent objects farther away from the imaging system. This results in progressively worsening position resolution by increasing distance of the objective lens or imaging system. As with normal objective lenses, normal or aspheric refractive surfaces are used so that objects remote from the imaging system cannot be sufficiently projected from each other. Although not known in the literature for the imaging of such objects, the use of optical imaging members optimized for this particular purpose may be required.

In European Patent Publication EP 0 358 628 A2, entitled "Visual navigation and obstacle avoidance structured light system", a triangulation system for application to a mobile vehicle is known, and the system using a clown light and a general objective lens is known. It works in an imaging system. The disadvantage of this method is that on the one hand the vehicle can only detect the object located in front of the direction of motion, and on the other hand, by using a general objective lens, only a close area with a limited area or an appropriate resolution can be used for measuring the distance of the object. Can be.

By R. A. Jarvis, J. C. Byrne, "An automated guided vehicle with map building and path finding capabilities"; R. C. Bolles, published by B. Roth, 4th International Symposium on Robotics Research, p. 497-504, 1998; And, “Map based navigation of the mobile robot using omnidirectional image sensor COPIS, Proc.,” At Y. Yagi, Y. Nishizawa, M. Yachida at the 1992 IEEE International Conference on Robotics and Automation in Nice, May 1992. It is known to perform peripheral imaging using a spherical mirror and its objective lens, the spherical mirror used does not change the resolution of the system when the objective lens is spaced apart. J. Hong, X. Tan, B. Pinette, R. Weiss, EM Riseman at the 1991 International Conference on Robotics and Automation in Sacramento, California, April 1991, “Image-based Homing, Proc. It is well known in the document to perform peripheral imaging using spherical balls. However, no clown lights are introduced in this case that can be used for triangulation. Such a so-called passive system has the disadvantage that it is very difficult to infer positional information because triangulation cannot be carried out because the object is not illuminated by light rays of known altitude. Evaluation requires the use of real-time image processing systems that require high costs for calculator capacity. See also P. Greguss, "PAL-optik basierende Instrumente fuer Raumforschung und Robot-Technik, in Laser und Optoelektronik 28 (5) / 1996, p. 43-49. The PAL-objective of Greguss is a wide-angle imaging member that has two aspherical surfaces that reflect and refract and project a full half-space, and the document also uses an obstacle for robots, which uses active triangulation. It is known to use PAL-optical means as recognition systems.

The present invention relates to an optical sensor system for detecting an object and measuring the position of the object. Preferably the sensor system is installed in an autonomous mobile system, thereby enabling orientation in unfamiliar environments.

1 illustrates an embodiment of a sensor system:

2 is a side view of a possible structure of the possible used;

3 is a schematic of a possible device for generating a clown around a sensor system;

4 shows a second embodiment of a possible device for generating a clown around a sensor system;

5 is a second embodiment for generating a clown around an imaging device;

6 is a side view of a possible structure of a sensor system of a vehicle or a robot;

7 is a plan view of the sensor system and the vehicle;

8 is a sensor system for using a one-dimensional photoelectric converter;

9 is an embodiment of a two-dimensional light position detector.

It is an object of the present invention to provide an optical sensor system that can be used, for example, in a mobile vehicle such as an autonomous mobile robot, which is simply technically blood donated, and which enables the detection of obstacles in all directions around the vehicle. The imaging system of the system is positioned not only within 50 cm of the object from the system, but also at a distance of 2 m or more.

This object is achieved according to the features of claim 1. Improvements of the invention are set out in the dependent claims.

Preferably the described sensor system consists of a light source that illuminates the perimeter of the autonomous mobile unit in the form of a clown around the unit. This is because it can simultaneously detect obstacles or objects on the main unit surface. Also preferably a plurality of light sources can be provided arranged in layers with each other, and the light sources can be connected at different intervals over time so that different elevation dimensions of the space can be detected or measured. Preferably light scattered from an illuminated object is carried out in combination with an objective lens, a filter and a photoelectric transducer, through the use of a wide angle specific imaging member having only one arcuate spherical or aspheric reflective surface, the surroundings of which are imaged Projected on the transducer by the system. By this structure, the object of the present invention can be achieved at the lowest possible technical cost. Preferably in the refinement of the invention the best spatial covering and the best position resolution are achieved and the shape of the aspherical reflective surface of the wide angle imaging member, using the spline-function, is described. The spline function represents the shape of the imaging member in the following manner. That is, according to the type of the objective lens used through the spline function, the farther area is enlarged and displayed, and the partial area of the aspherical imaging member, which is suitable for the far area and each far area, is displayed, so that each transition point of the detection area is displayed. My polynomial function has the same value and the same derivative. The function used is contiguous and indivisible. By using the imaging member, a simple objective lens, preferably having a general viewing angle, can be used for the wide angle linearity imaging characteristic curve required for the refinement of the invention. By introducing spline-functions, the distracted light from distant areas is pre-distorted as intended before being transmitted by the objective lens, so that the farther areas may be displayed with higher resolution than by the normally used objective lens. Can be. In this way an imaging system is used which provides a simple and economical method for producing a wide angle, linear light system.

The embodiments of the present invention are described in detail below with reference to the drawings.

As shown in FIG. 1, there is a possible embodiment of the known sensor system which illuminates around the space vastity by four light sources 1. In the construction of the light source for illumination of the clown it should be noted that the clown is in particular lying in a plane parallel to the pedestal to which the autonomous mobile unit equipped with the sensor moves. If such a parallel plane structure is not possible, triangulation becomes difficult, and triangulation differs for triangulation for measuring the distance of an object by illuminating a reflective object at different relative positions of said ray upon evaluation of the reflected ray. Note that the angle is given. At this time, the light source 1 generates the clown 2 which illuminates the space. The imaging member 4 used projects the light scattered from the object 3 through the objective lens 6 onto the photoelectric converter 7, and the photoelectric converter as a two-dimensional CCD-image detector of the camera 5. Implemented in the device. The photoelectric converter 7 is present in combination with an electronic evaluation device 8, which is part of a sensor system for measuring object position, for example, present in a calculator. The electronic evaluation device 8 measures the position of the object 3 using the principle of active light triangulation according to the image projected on the photoelectric converter 7, in particular the objective lens 6 and the imaging member 4. ) Is used in combination with the height of the plane in which the rays are illuminated. Preferably the sensor system is installed in a mobile vehicle 12 such as a mobile robot. In this case, actual information about the control of the vehicle 12 or the robot is measured from the electronic evaluation device 8, and another running section (distance) of the unit is determined according to the result of the information. The information informs, for example, of the position of the object 3, and the vehicle 12 must move through and under the object or between the objects.

In the embodiment shown in FIG. 1, the optical axis of the imaging member 4 is preferably arranged perpendicularly to the clown 2 emitted from the light source 1. In this embodiment, the imaging member 4 is spherical as a light member having a spherical or aspheric reflective surface 9, and the outside of the reflective surface 9 is inserted into the imaging system for imaging of the reflected rays. The light emitted from the clown and the object 3 emitted from the light source is passed through the object 3 by the imaging member 4, as shown schematically by the numerically indicated beam path. 7) is radiated. The distance of the light beams impinging on the light detector 7 is characterized with respect to the distance of the object 3 from the sensor system according to the imaging properties of the object and the imaging member 4. In the embodiment of the sensor system shown in FIG. 1, each two-dimensional image detector 7 can be installed. For example, a photodiode matrix can be used as the photoelectric converter 7 instead of the two-dimensional CCD-sensor.

2 is a side view of a possible basic embodiment of the applied light source 1. The light source 1 shown in FIG. 2 is preferably composed of a cylindrical mirror 11 having an aspherical cross section and a luminous body 10, which may for example be a light emitting diode. The light emitter is present in the focal line of the cylindrical mirror 11. The light emitters 10 are arranged in order on the focal line of the aspherical cylindrical mirror 11 such that the emitted surface of the light emitter 10 faces the aspherical cylindrical mirror 11. The light emitted from the illuminant 10 first reaches the aspherical cylindrical mirror 11 and then is emitted and projected through the mirror as a clown 2. By introducing an aspherical mirror shape matched to the luminous body 10, the clowns with the light sources 1 side by side can be illuminated. In this regard, light emitting diodes (LEDs) can be inexpensive and simple small light sources, and the selected structure of light emitting diodes allows the use of inexpensive light sources on the axis of the cylindrical mirror.

3 shows a possible basic structure for generating the clown 2 from part of the cylindrical mirror. Since the cylindrical mirror 11 here is a so-called off-axis structure with respect to the light emitting body 10, only a part of the cylindrical mirror 11 shown in FIG. 2 is used. In this case, preferably, the light emitter 10 is formed as an LED, and is sequentially arranged in the focal line of the aspherical cylindrical mirror, so that the lighted surface of the light emitting body is directed toward the aspherical cylindrical mirror. The light source likewise generates light rays which are effectively parallel to the sensor system. This is indicated by the radiation path indicated by the arrow.

As shown in FIG. 4, another possible way to generate the clown 2 for illuminating the periphery of the imaging device is for the parallel rays to rotate and be displaced. The rotary light beam 2 is generated in such a way that the luminous body 10 and the collimator lens 14 are displaced while rotating about the axis t. In another embodiment, the light emitter 10 and the collimator lens 14 are fixed and rotated around through a mirror in which the light beam 2 rotates.

5 shows a second possible embodiment for generating the clown 2 radiating around. In this embodiment, the clown 2 is generated by the conical mirror 15. In this case the light emitted from the illuminant 10 first becomes parallel through the collimator lens 14 and then extends through the conical mirror 15 to the desired clown 2. In this embodiment, for example, an incandescent lamp, a halogen lamp, an arc lamp or a laser may be used as the light emitter 10.

6 shows a possible structure of the sensor system installed in the autonomous mobile unit 12, which may be, for example, a service robot. 6 is a side view. Preferably, a plurality of light rays arranged in layers can be generated in the mobile system, which light rays are emitted from the plurality of light sources 1 layered. Preferably, the clowns 2 are displaced from one another with time, pulsating and radiating. Multiple layered light sources can reach better level deviations of obstacles. In order to be able to detect and measure all obstacles around the mobile vehicle 12 as much as possible, two imaging members 4 are preferably provided with two accessory cameras positioned at opposite corners of the mobile vehicle 12. . It is ensured that the corresponding level position of the actually connected light source is taken into account for evaluating the triangulation result when triangulating the obstacle via the electronic evaluation device.

7 is a plan view of a mobile vehicle 12 equipped with a sensor system, such as a robot having a receiving area of the detection system 13, for example. As shown in FIG. 7, a separate imaging member 4 is provided at each of the two opposed edges of the movable system 12. If two separate imaging members 4 are arranged in the same manner as shown in FIG. 7, the detection area 13 of the optical sensor system can be extended to the entire periphery of the mobile system 12 or the entire space surrounding the mobile system. Can be.

A possible embodiment of the photoelectric converter 7 is shown in the form of a one-dimensional photoelectric converter 7 in FIG. 8. Light from the imaging member 4 is projected through the objective lens 6 to a one-dimensional light detector which moves or preferably rotates in the hyperplane. The photoelectric converter 7 can be implemented, for example, as a one-dimensional position sensing detector such as a CCD or a PSD. The one-dimensional photodetector detects the entire in-plane intensity distribution by moving or preferably rotating within the hyperplane, on which the imaging member 4 and the objective lens 6 image the spatial region around the mobile vehicle 12. do. In this way a measurement result is obtained, preferably intermediate storage or simultaneous evaluation of the number of revolutions of the photoelectric sensor.

9 shows another possible embodiment of the photoelectric converter 7, in which the photoelectric converter 7 is shown as a two-dimensional position sensing detector. In this embodiment, the photoelectric converter 7 is executed as a two-dimensional position sensing detector present behind the in-plane objective lens 6 thereof. In the present embodiment there is a non-transmissive disc 16 with a gap 17 between the objective lens 6 and the photoelectric converter 7. The area above the position sensing detector, which is actually covered by the gap 17 when the disc rotates, is always open. For example, the gap 17 of the optically transmissive disc 16 can only transmit light in a suitably defined spatial region having an opening angle of 1 °. In this way it is possible to reach directional resolutions which do not have any angle at all. The width of the gap to be selected depends on the amount of light being disturbed or the sensitivity of the detector and the intensity of the light emitted from the light source. As shown in the embodiment of Fig. 4, when the rotating parallel light beam is used as the clown 2, it is not necessary to use the original plate 16 because the directional resolution is already fixed by the rotating light source. In short, the advantage is achieved with the described sensor system that the receiving area is larger than in the known embodiment, and that the imaging is the same as other known sensor systems by triangulation. Through wide angle imaging, the position of an object distant from the sensor system can be measured. In this case, the specific shape of the imaging member 4 guarantees the same distance measuring resolution within the entire detection area of the sensor system, and corrects almost insufficient resolution of the objective lens 6 within the distance of the sensor system. This is because light rays reflected from there are scattered, so that further objects are dispersed.

Claims (14)

An optical sensor system for detecting object position, comprising a photoelectric converter and a light source for ambient lighting, which converts a distribution of intensity of light scattered by an object into an electrical signal and transmits the signal to a sensor signal evaluation system. A light source 1 in which the sensor system generates one or a plurality of clowns in a horizontal direction in a plurality of spatial directions, and An optical sensor system, characterized in that it comprises an optical imaging member (4) having only one reflective surface (9) for reflecting and projecting the light disturbed by an object (3) to the photoelectric converter (7). The method of claim 1, Optical sensor system, characterized in that it comprises an objective lens (6) in the beam path between the imaging member (4) and the photoelectric converter (7). The method according to claim 1 or 2, Optical sensor system, characterized in that the optical axis of the imaging member (4) is perpendicular to the illuminated clown (2) and has four light sources (1). The method according to any one of claims 1 to 4, Optical sensor system, characterized in that it comprises a wide-angle imaging member (4), with only one spherical or aspherical reflective surface (9). The method according to any one of claims 1 to 4, Optical sensor system, characterized in that the imaging member (4) has at least one aspherical reflective surface (9) operable with two spline-functions. The method according to any one of claims 1 to 5, Optical sensor system, characterized in that it has at least two light sources (1) layered in order to generate two layered clowns (2). The method according to any one of claims 1 to 6, And a one-dimensional position sensing light detector movable as said photoelectric converter (7). The method according to any one of claims 1 to 6, The optical sensor system, characterized in that it has a two-dimensional position sensing detector as the photoelectric transducer (7), and a stereoscopic light modulator is installed in the beam path between the imaging member (4) and the photoelectric transducer (7). The method of claim 8, An optical sensor system, characterized in that a rotary disc (16) having a gap or a liquid crystal modulator is provided as the stereoscopic light modulator. The method according to any one of claims 1 to 6, Optical sensor system, characterized in that the photoelectric converter (7) is implemented as a two-dimensional image detector matrix. The method according to any one of claims 1 to 5, Light sensor system, characterized in that the light source (1) is implemented as a rotary light source. The method according to any one of claims 1 to 10, The light source 1 is formed of a light emitting element 10 and consists of a cylindrical reflecting surface 11 having an aspherical cross section, the light emitting element 10 being arranged as a light emitting diode in the focal line of the cylindrical reflecting surface 11. Thereby the light emitting surface of the element (10) is directed towards the cylindrical mirror (11). The method according to any one of claims 1 to 10, An optical sensor system characterized in that the light source (1) for generating a clown from a known light emitting element such as a fluorescent lamp, a halogen lamp, an arc lamp or a laser is formed as a collimator lens (14) and a spherical mirror (15). An autonomous moving unit having a sensor system according to claim 1.