Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Automatic route guidance vehicle
Reexamination Certificate
2000-05-12
2001-08-21
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Automatic route guidance vehicle
C358S461000, C180S168000, C180S169000, C901S001000, C901S046000, C901S047000
Reexamination Certificate
active
06278917
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention is directed to a method with which autonomous mobile units can be brought into a parked position.
Autonomous mobile units can, for example, be employed in office, hospital or industrial environments in order to carry out simple tasks such as, for example, transport, remote manipulation or cleaning jobs. Upon utilization of such autonomous mobile robots, for example, it is desirable that these can dock precisely in order, for example, to be able to accept or hand over goods in a docking station, change a battery or, for example, replace the cleaning device in a cleaning machine. Another docking case can occur when the autonomous mobile unit is to travel into a garage in which it waits until further activity requests are made of it. During this waiting time, for example, an accumulator that is provided in the autonomous mobile unit can be charged or a self-diagnosis of the device can be undertaken.
One problem that occurs when docking such units is comprised therein that the device must be brought from an arbitrary starting configuration into a fully defined final position. Known autonomous mobile units as disclosed, for example, by German Patent P 44 21 805 orient themselves with ultrasound sensors and on the basis of odometry measurements that are undertaken at a wheel of the unit. While the device is travelling from a starting point to a destination point, the configuration errors produced by the sensor imprecisions in the odometry measurement and in the ultrasound distance measurement sum up, so that an exact orientation is soon no longer possible when no counter-measures are undertaken. In said patent, counter-measures are undertaken in such a form that different activities that the autonomous mobile unit is to perform are evaluated and the configuration errors are thereby monitored. Correction measures are initiated when too great an error occurs.
Another problem is comprised therein that the autonomous mobile unit should preferably dock in a docking station in a well-defined rotational orientation and with a very specific outside at the docking station. As a rule, however, such autonomous mobile units comprise a three-wheel kinematics which does not enable them to move arbitrarily on the ground. The three-wheel kinematics of autonomous mobile units is discussed, for example, in German Patent 195 21 358. The slippage that sums up over a planned travel path of such an autonomous mobile unit is thus determined therein.
SUMMARY OF THE INVENTION
The problem underlying the invention is thus comprised in specifying a method with which an autonomous mobile unit can be brought into a defined final position in a docking station.
This and other problems are solved with a method for docking positioning of an autonomous mobile unit at a docking device using a guide beam including the first step of prescribing destination coordinates and a rotated attitude of the docking device in a world coordinate system at commencement of travel of the autonomous mobile unit thereby affording the autonomous mobile unit information concerning alignment with the guide beam and position and rotated attitude of the autonomous mobile unit. Next, self-orienting of the autonomous mobile unit is performed in surroundings of the autonomous mobile unit using at least one distance measuring sensor with which the autonomous mobile unit measures a distance to an obstacle in the surroundings and odometry, with which the autonomous mobile unit measures a path distance traversed the commencement of travel. Also, the autonomous mobile unit calculates coordinance of the autonomous mobile unit in the world coordinate system and positional uncertainty of the autonomous mobile unit based on at least one of the measurements of distance to an obstacle and the traverse path distance. The autonomous mobile unit is then moved to a starting position for a docking of then wherein the autonomous mobile unit aligns with respect to the rotated attitude of the autonomous mobile unit such that a detector for detecting the guide beam and the guide beam can interact. Finally, the autonomous mobile unit is moved in the direction of the destination coordinance when the detector does not detect the guide beam in order to seek the guide beam wherein the movement of the autonomous mobile unit in the direction of the destination coordinance in conjunction with the detector for detecting the guide beam is used for docking positioning of the autonomous mobile unit.
One particular advantage of the method is that a good orientation aid in the form of a guide beam with which a signal for a travel path control of the unit can be generated for approaching the docking position is made available by employing a slot-shaped light beam residing perpendicular on the motion substratum of the unit in combination with a position-sensitive detector for this guide beam that is attached parallel to the travel surface of the unit.
Another advantage of the method is that it provides two detection means for the guide beam that are arranged following one another in a principal approach direction of the unit; a more exact alignment of the unit with reference to the docking means can thus be achieved.
Another advantage of the method is that it can be utilized with commercially obtainable position-sensitive detectors.
An autonomous mobile unit works especially advantageously with a docking method wherein it determines its relative configuration vis a vis the docking means on the basis of the emitted guide beam and determines on the basis of its three-wheel kinematics whether it can designationally reach the docking means proceeding from this configuration in order to be able to dock thereat. When this is not the case, it independently moves away therefrom and centers itself with reference to the docking means. This method has the advantage that no information whatsoever are required about the environment of the docking means and that it can be realized in a simple way.
Given the inventive docking method, however, information about the environment of the docking means can also be advantageously utilized in that, for example, a known distance of the docking means from a side wall is measured by the autonomous mobile unit and conclusions about the position of the docking means are drawn therefrom. The exact position of the unit can then be determined with an additional distance-measuring sensor, with which the distance from the docking means is measured, and the docking procedure can be initiated.
The fact is especially advantageously utilized in the inventive docking method that the unit knows its position errors and that its starting configuration (i.e., the starting position and the starting rotational attitude in relationship to the position and rotational attitude of the docking means and of the guide beam) is likewise known, and the unit, on the basis of the estimated position error, can thus determine exactly that location at which the guide beam is not yet acquired by the sensors. This has the great advantage that the direction in which the guide beam must be sought is exactly known or, the unit can thus minimize its positional uncertainty transversely relative to the guide beam when the guide beam is already incident onto the detectors at this point in time.
In a development of the inventive docking method, the fact is advantageously utilized that motion of the autonomous mobile unit in its starting configuration can be resolved into a forward motion and a rotary motion, so that the unit need not travel a loop in constricted surroundings but can implement forward travel and subsequently implements a rotational movement in place or, respectively, implements this motion event in the reverse sequence in order to proceed into a starting configuration for the docking event.
In a development of the inventive method, the unit especially advantageously moves forward or backward to its staring position since the local conditions can be utilized better in this way (i.e., the unit need not necessarily turn in place but can turn
Bauer Rudolf
Zillich Michael
Cuchlinski Jr. William A.
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
To Tuan C
LandOfFree
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