Optics: measuring and testing – By polarized light examination – With light attenuation
Reexamination Certificate
1999-03-30
2001-06-12
Kim, Robert H. (Department: 2877)
Optics: measuring and testing
By polarized light examination
With light attenuation
36
Reexamination Certificate
active
06246476
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for controlling the movement of a moveable first object relative to a second object, and namely with the aid of optical sensing of the second object or a part thereof by means of an optical sensing system, with recognition of a pre-determined pattern and/or a structure present on the second object, wherein corresponding structures are stored in a memory device, and wherein the first and the second objects are approached from a position in which they are spaced apart into engagement with one another.
The present invention also relates to an apparatus for controlling the movement of a moveable first object relative to a second object, with drive and control devices for at least one of the objects, a pattern memory device and a pattern recognition device, and an optical sensing device for patterns and/or structures selected for or applied to the second object.
2. Discussion of Related Art
Corresponding methods and apparatus are known from so-called robotics and robot technology. With the method and the apparatus from which the present invention proceeds, for example, a tool fitted on the end of a robot arm must engage with an object, which itself can be moveable, so its position is not exactly defined from the outset but must first be sensed by an optical sensing device in order to bring the robot arm and the tool fitted onto it into engagement with the second object concerned in a well-directed manner. The fact that the position of the second object with which the first object or part of the first object has to be brought into engagement is not defined from the outset, differentiates such methods and apparatus, for example, from other automated machines such as, for example, machine tools with tool changing devices in which different tools are arranged in a tool magazine at precisely defined positions, so an automatic tool change can take place without the respective tools having to be optically sensed.
With other methods and apparatus, for example, a tool, a reading head or another device is continuously passed at a substantially fixed distance above the surface or parts of the surface of a second object. Here too, parts of the first object can be in engagement with parts of the second object. However it is not the procedure of bringing the first object closer to the second object which is controlled, but simply the movement of the parts engaged with one another relative to one another, for example, the movement of a welding device along a welding path, wherein the seam site of the parts to be welded together is optically sensed and continuously followed. During this movement control, no approaching takes place, but instead the distance is kept constant with the aid of an appropriate feed-back control system.
SUMMARY OF THE INVENTION
With the methods and apparatus from which the present invention proceeds, a two-stage movement is usual, for example, wherein first, in accordance with a predetermined movement program, a first approaching movement takes place which brings the first object or the parts to be brought into engagement with one another, into a roughly estimated close proximity, in which, however, because of the circumstances and the boundary conditions, such as for example the ranges of movement of the two objects, coming into contact is still excluded for the time being. An optical position measurement of the parts to be brought into engagement is then carried out, and the remainder of the movement done under the control of the drive device of the first object according to the coordinates sensed in the previous position. During this last portion of the movement, however, there is no longer any control and correction of the movement. The latter can be a problem above all where unexpected further movements of the second object are possible, or when the second object carries on moving, in particular, when it does not move at a regular speed. While smooth movements of the second object can be taken into account with the conventional method and the corresponding apparatus, it is no longer possible with unexpected, unpredictable or irregular movements of the second object relative to the first object. The setting of the preliminary position in which the two objects are first brought roughly close together is only useful and possible without problems when the movement range of the second object relative to the first one is limited during the approaching movement, that is to say, when it is definite that the second object or those parts of the second object which have to be brought into engagement with parts of the first object is located within a relatively small, predetermined space.
These criteria cannot always be satisfied in practice, however. For example, with advancing automation, there is a need for an automatic refuelling system, in which a driver drives his car into the area in front of an automatic fuel pump and, for example, opens the filler flap from inside, whereupon a fuel hose is automatically conveyed to the fuel tank inlet and is coupled with the fuel tank inlet, and then filling up of the vehicle can take place automatically. Such a system is very pleasant for the customer, as he need not wait for service personnel, nor worry about soiling his hands with fuel or oil as often happens when touching conventional fuel pump nozzles at filling stations. A fuel station of this type could save on personnel and thus on costs with such a system. There is nevertheless a problem that the driver cannot always drive his vehicle exactly into a predetermined position, but instead the position which he has to occupy during refuelling can only be very roughly predetermined as it would not be possible for most drivers to position their vehicle exactly to the centimeter. Moreover, the fuel tank inlets are at different heights on different vehicles, and also fitted at different distances from the front or rear part of the vehicle, so even an appropriate control and positioning for the driver, as is known, for example, from car washes, would only make a very rough positioning of the fuel tank inlet possible. Even with a special setting for a particular type of vehicle, these positions could vary due to different loading conditions of the vehicle. Lastly, the position of the fuel tank inlet can also change when the approach procedure has already started because of rolling movements due to the design of the vehicle.
It is clear that the present invention is not primarily directed towards automatic refuelling systems, but instead that this example has simply been presented here for the purpose of making the problems occurring with many approach procedures clearly understandable, when the second object remains moveable relative to the first object, and/or cannot be exactly positioned.
Compared to the prior art described herein above, the object of the present invention is to provide a method and apparatus with the features described in the introduction, which make possible a secure engagement of the parts of the first and second objects to be brought into engagement with one another, even when the second object can perform more or less uncontrollable movements with respect to the first object during the approach movement, and/or when the position which the second object can take up can only be very roughly established. It is clear that the parts of the second object which are to be brought into contact with the parts of the first object must nevertheless always lie within the range of movement or within reach of the latter.
With respect to the method described in the introduction, the object of the invention is solved in that the approach of the first object to the second is done with continuous sensing of the structures of the second object by the sensing device of the first object, wherein the distance between the parts of the first and second objects to be brought into engagement with one another are continuously sensed, either directly or indirectly, and wherein the movement control
Frohn Heiko
Lehn Norbert
Baker & Maxham
Kim Robert H.
Nguyen Cang H.
Vitronic Dr.-Ing. Stein
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