Abstract:
In an arrangement and method for determining a spatial position of an object on a thermal basis, an imaging thermal sensor detects a thermal image of the environment and outputs corresponding signals to a processing unit coupled to the sensor. The processing unit accepts the signals, evaluates the image in view of a thermal marking, and determines the spatial position of the object dependent on the marking. The arrangement and the method can be employed in combination with a robot for orientation and for travel path control of the robot.

Description:
BACKGROUND OF THE INVENTION 
     The invention is directed to the determination of a spatial position of an object. 
     The use of an autonomous robot system in industry is steadily increasing. The point of departure was the use of a robot system in fabrication. This robot system was thereby utilized in stationary fashion in order to implement repetitive but unchanging and permanently prescribed motion sequences. The demand for precision is thereby in the foreground. The disadvantage of this robot system is that it is bound to a location and, thus, has little flexibility. 
     T. Cord et al., Mobile autonome Roboter zum Transport von Containern, 11. Fachgespräch, Karlsruhe, Eds. R. Dillmann, U. Rembold, T. Lüth, Springer Verlag, Berlin, Heidelberg, New York, pp. 1-9, 1995 discloses a mobile robot system that is no longer stationary but can move by itself. The navigation of the movement is thereby accomplished with specific preparations in the environment of the robot. 
     One example of this robot system is the driverless transport system that is used for transporting materials. This system is usually track-guided, i.e. it follows a fixed path. This concept has proven itself in practice but has the disadvantage that it is extremely inflexible—see DE 35 369 74 A1. This is to be attributed thereto that the navigation control of the robot system ensues with a permanently present guide track Cord et al, supra. Before the transport robot is placed in operation, this is permanently introduced into the floor in the form of an electrical conductor along the travel path. An involved re-laying of the conductor is required given a change of the path guidance. The old conductor must be removed from the floor, the floor covering must be repaired, the new path guidance must be defined and the conductor must be placed into the floor along the new path. This denotes a great time expenditure and high costs. 
     R. Bauer, Integriertes hieracrhisches Navigationssystem für autonome mobile Roboter, pp. 17-23, pp. 35-41, Dissertation, Linz University, 1997 discloses an autonomous mobile robot system that is in the position of orienting itself, navigating and autonomously implementing a predetermined task in a dynamically changing environment completely independently without requiring a great expense for the preparation of the environment. 
     Various types of a position identification and navigation system have been developed therefor—Bauer. Such a system usually works on the basis of an imaging sensor. A sensor that detects the surroundings of the robot is thereby attached to the robot. Upon employment of a standard programmable computer, the sensor data are interpreted and a plot of the environment, similar to a map, is built up. 
     This map is interpreted in computer-supported fashion. Taking the kinematic and geometrical properties as well as the current position of the robot into consideration, the best possible navigation for a predetermined task is identified—DE 44 157 36 A1. 
     It is known from Bauer to employ an ultrasound sensor, a laser sensor or a stereo camera system as the sensor in a mobile robot. 
     The sensor system known from Bauer, however, exhibits a variety of disadvantages. Thus, the laser sensor or the stereo camera system is too expensive for the measurement use. In contrast thereto, the ultrasound sensor in fact has a low price and great ruggedness. However, the precision of such a sensor, its susceptibility to disturbance with respect to a temperature fluctuation, an external signal or a multiple reflection and the low range of the sensor make the use thereof only conditionally possible. 
     R. Bruchhaus, D. Pitzer, R. Primig, M. Schreiter, W. Wersing, N. Neumann, N. Hess, J. Vollheim, R. Köhler, M. Simon, An 11×6 Element Pyroelectric Detector Array Utilizing Self-Polarized PZT Thin Film Grown by Sputtering, Integrated Ferroelectrics, Vol. 17, pp. 369-376, 1997 also discloses that a pyroelectric material be employed for the development of a thermal sensor. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to determine the spatial position of an object in a flexible and cost-beneficial way. 
     According to the arrangement of the invention for determining a spatial position of the first object, an imaging thermal sensor is provided. A processing unit coupled to the sensor is provided with which a spatial position of the first object is identifiable from corresponding signals of the sensor with reference to at least one thermal marking that is acquired by the sensor. In a method of the invention for determining a spatial position of the first object with an imaging thermal sensor and a processing unit coupled to the sensor, with the sensor detecting a thermal image of the environment and outputting corresponding signals to the processing unit. With the processing unit, accepting the signals, evaluating the image in view of at least one thermal marking, and determining a spatial position of the first object dependent on the marking. 
     The arrangement for determining a spatial position of a first object comprises an imaging thermal sensor and a processing unit coupled to the sensor. The processing unit is configured such that the spatial position of the first object can be determined from corresponding signals of the sensor on the basis of at least one thermal marking that is acquired by the thermal sensor. 
     An object whose temperature differs from an ambient temperature is employed as thermal marking. The ambient temperature is the temperature in the environment of the first object. 
     In the method for determining a spatial position of a first object with an imaging thermal sensor and a processing unit coupled to the sensor, the following steps are implemented: 
     a) the sensor detects a thermal image of the environment and outputs corresponding signals to the processing unit; 
     b) the processing unit picks up the signals, evaluates the image in view of at least one thermal marking and determines the spatial position of the first object dependent on the marking. 
     The invention creates a very simple and cost-beneficial system for position determination since low costs are incurred both for the production of the imaging thermal sensor as well as for the creation of a thermal marking. 
     In particular, the possibility of being able to use a heat source that already exists, for instance a lighting member, or a thermal track that has arisen in a natural way, for instance a damp cleaning track, as the thermal marking make the invention attractive and practical. 
     In addition to these advantages, the employment of a thermal marking has the advantage that it is usually not visible for a person and is thus not disturbing. 
     The imaging thermal sensor is preferably a sensor with a pyroelectric thin-film. The sensor can thus be implemented as a very small and cost-beneficial component part. 
     It is provided in a further development that the arrangement comprises a unit that acts such on a second object such that the temperature of the second object differs from an ambient temperature and the second object can be recognized as the thermal marking. The advantage of this embodiment is comprised therein that a system that can be very flexibly utilized results due to the interaction of the first and second object. 
     The unit is preferably configured such that the second object is moistened with fluid, as a result whereof the temperature of the second object differs from the ambient temperature. And the second object can be recognized as the thermal marking. The advantage of this embodiment is comprised in the extremely simple and cost-beneficial way in which the thermal marking is produced. 
     Another advantageous development in view of the simplicity and compactness of the arrangement derives when the unit that acts on the subject object is the first object. 
     An especially simple structure of the arrangement derives when the imaging thermal sensor is attached to the first object. 
     The arrangement is preferably utilized such that the first object is a robot. In this way, there is a very simple, flexible and economical system for position determination for the robot. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an orientation of a robot at a thermal track generated by the robot itself; 
     FIG. 2 shows orientation of a cleaning robot; 
     FIG. 3 shows securing against a hazardous region with a thermal marking; and 
     FIG. 4 illustrates recognition of a human obstacle. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     1. Orientation of a Robot at a Thermal Track Generated by the Robot Itself 
     FIG. 1 shows the orientation of a robot  103  at a thermal track  104  generated by the robot  103  itself. 
     By heating a sector  111  of a rear wheel  101  of the robot  103  with a heating element  102  worked into the rear wheel  101 , the robot  103  heats elements at the floor  104  at predetermined intervals while travelling. Until they have completely cooled, these heated floor elements  104  act on the ambient temperature as thermal markings and form the thermal track  104 . 
     The imaging thermal sensor  105  attached to the back side  112  of the robot  103  detects an ambient image  114  directed opposite the travel direction  113  of the robot  103  at predetermined time intervals. The sensor  105  is designed as described in Bruchaus et al. 
     Given straight-line travel of the robot  103 , the sensor  105  supplies a thermal ambient image  114  directed opposite the travel direction  113  wherein the detected thermal markings  104  exhibit a very specific order. Deviations from the straight-line travel leads to changes in the thermal image  114 . The thermal image  114  is stored in a processing unit  106  coupled to the sensor  105  that comprises a programmable processor  107  and a memory  108  that are connected to one another via a bus  109 . The processor  107  reads the thermal image  114  from the memory  108  and determines the nature and extent of the deviation from the predetermined travel direction  113  from the modification of the thermal image  114 . 
     The processor  107  determines a steering quantity therefrom that is transmitted to a steering unit  110  coupled to the processing unit  106 . Dependent on the transmitted steering quantity, the steering unit  110  positions the wheels  101 ,  115  of the robot such that the deviation from the straight-line travel is compensated. 
     2. Orientation of an Autonomous Cleaning Robot 
     FIG. 2 shows the orientation of the robot, which is utilized as cleaning robot  201 , at a fluid track  202  produced by the robot  201  itself. 
     Due to the dissipated evaporation energy of the fluid, damp floor elements  202  cool off compared to the ambient temperature and form a thermal track  202 . For orientation of the cleaning robot  201 , this is utilized for two steering tasks: 
     The cleaning robot  201  employs the self-generated thermal track  202 , as shown in exemplary embodiment 1, for controlling the straight-line travel  206 . 
     For an efficient cleaning of a surface  203  that is covered by adjoining cleaning paths  204   a-d  that proceed parallel to one another and are laterally offset by the width of the cleaning robot  201  and traversed by the cleaning robot  201  in alternating travel direction  207 , the cleaning robot  201  orients the cleaning path  204   b  being currently traversed by it with reference to the thermal track  202  that was generated while travelling on the previously traversed cleaning path  204   a.    
     The arrangement of the thermal sensor  105 , the structure and the functioning of the processing unit  106  is shown in exemplary embodiment 1. 
     3. Segregation from a Hazardozus Region with a Thermal Marking 
     Another exemplary embodiment is shown in FIG.  3  and is explained in greater detail below. 
     FIG. 3 shows an embodiment of the invention wherein the thermal sensor is employed in order to prevent the penetration of the robot  301  into a spatial region  302   a,b  demarcated with a thermal marking  303 . This is necessary when a region  302   a,b  of the room  302  accessible to the robot comprises a risk potential. Such a region  302   a,b  is the zone in the environment of an opening door  302   a  or a stair step  302   b;    
     For this purpose, a resistance wire  303  is let into the floor that limits the region  302   a,b  dangerous to the robot  301  at a prescribable safety distance. The resistance wire heats the adjacent floor elements  304  to a predetermined temperature and generates the thermal marking  304 . 
     A thermal sensor  306  that supplies the thermal ambient image in  312   a  travel direction  313  and opposite the  312   b  travel direction  313  of the robot  301  is attached to the front side  305   a  and to the back side  305   b  of the robot. The sensor  306  that is employed is designed as disclosed in Bruchhaus. 
     Due to the predetermined temperature, the thermal marking  304  expresses itself in this thermal image  312   a,b  in a way that can be unambiguously recognized by a processing unit  307 . 
     The thermal image  31     2 a,b  is stored in a processing unit  307  coupled to the sensor  306 , said processing unit  307  comprising a programmable processor  308  and a memory  309  that are connected to one another via a bus  310 . The processor  308  reads the thermal image  312   a,b  from the memory  309  and, based on the orientation of the thermal marking  304  in the thermal image  312   a,b , determines the position of the robot  301  relative to the thermal marking  304 . 
     Dependent on the identified position, the processor  308  calculates a steering quantity that is transmitted to a steering unit  311  coupled to the processing unit  307 . The steering unit  311  positions the wheels  314  of the robot  301  such dependent on the transmitted steering quantity such that the robot does not travel across the thermal marking  304 . 
     4. Recognizing a Human Obstacle 
     Another exemplary embodiment is shown in FIG.  4  and is explained in greater detail below. 
     When a mobile robot  401  is placed in a room  402  that is accessible to a person  403 , then the person  403  located in this room represents an obstacle for the robot  401 . Due, however, to the natural body heat, the person  403  is recognized as a human-specific thermal marking. 
     A thermal sensor  405  that supplies the thermal ambient image in  412   a  travel direction  413  and opposite  412   b  the travel direction  413  of the robot  401  is attached to the front side  405   a  and to the back side  405   b  of the robot. The sensor  405  that is employed is designed as disclosed in Bruchhaus. 
     Due to the body heat, the human-specific thermal marking  403  expresses itself in this thermal image  412   a,b  in a way that can be unambiguously recognized by a processing unit  406 . 
     The thermal image  412   a,b  is stored in a processing unit  406  coupled to the sensor  405 , said processing unit  406  comprising a programmable processor  407  and a memory  408  that are connected to one another via a bus  409 . The processor  407  reads the thermal image  412   a,b  from the memory  408  and, based on the orientation of the thermal marking  404  in the thermal image  412   a,b,  determines the position of the robot  401  relative to the thermal marking  403 . 
     Dependent on the identified position, the processor  407  calculates a steering quantity that is transmitted to a steering unit  410  coupled to the processing unit  406 . The steering unit  410  positions the wheels  414  of the robot  401  dependent on the transmitted steering quantity such that the robot travels around the thermal marking  403  at a predetermined safety distance. 
     A few modifications of the above-described exemplary embodiment are explained below. 
     In order to prevent a collision between the robot  401  and the person  403 , the steering unit  410 , dependent on the identified position of the robot  401 , can stop the travel by shutting off the robot  401 . 
     It is also provided to attach a warning device  411  to the robot  401  that supplies an audio-visual alarm signal dependent on the identified position of the robot  401 . 
     Although various minor changes and modifications might be proposed by those skilled in the art, it will be understood that my wish is to include within the claims of the patent warranted hereon all such changes and modifications as reasonably come within my contribution to the art.