Patent Application: US-36274509-A

Abstract:
manufacturing processes profit greatly from a close collaboration between human and machine . whereas a human behaves flexibly and adaptively but is inclined to make mistakes during repetitive work operations , machines operate quickly and exactly but are static and not very flexible . in order to enable an improved hazard protection in the context of a safe human - machine interaction , a spatial - and time - dependent variable degree of hazard is allocated to monitored spatial areas as a function of the current position and the current movement state of a machine or a machine element , as well as of the observed person . for this purpose , a multicamera system is used to acquire image data of the person in order to obtain the most detailed information possible about the position and alignment of a person , in particular also with reference to the body parts thereof , in an industrial environment . these image data are then examined with regard to the imaging of a person so that whenever a person has been detected in the image data , an articulated virtual 3d model of the human body is matched to this person hypothesis . subsequently , this virtual body model is continuously matched to the movement behavior of the person detected in the image data . a hazard potential is determined using knowledge of the position and the movement behavior of the virtual body model in space . the hazard potential thus determined is subjected to a threshold value comparison in order to act upon the movement control of the machine or the machine part in the event of this threshold value being exceeded .

Description:
in order to obtain the most detailed information possible about the position and alignment of a person , in particular also with reference to body parts thereof , in an industrial environment , image data of the person are acquired by means of a multi - camera system . these image data are then examined with regard to the imaging of a person such that whenever a person has been detected in the image data an articulated , virtual 3d model of the human body is matched to this person hypothesis . subsequently , this virtual body model is continuously matched to the movement behavior of the person detected in the image data . in a first refinement of the observation of a person in an industrial environment , the position and / or the movement behavior of a machine or a machine element located in the environment of the person is determined . a hazard potential can be determined starting from knowledge of the position and of the movement behavior of the virtual body model in space . the hazard potential thus determined is subjected to a threshold value comparison in order to act upon the movement control of the machine or the machine part in the event of this threshold value being exceeded . in a particularly advantageous way , acting upon the movement control of the machine or the machine part effects a shutdown thereof or a slowing down of the movement thereof . if only a slowing down of the movement is effected , the machine or its movable machine element is able to continue the work operation with a simultaneous reduction in the hazard potential . this way of observing persons renders it possible in a particularly advantageous way to apply the method for securing a hazard in the context of reliable human / machine interaction . it is thereby possible to allocate a location - and time - dependent variable degree of hazard to the monitored spatial areas as a function of the current position and the current movement state of a machine or a machine element , as well as of the observed person . in the alternative refinement of the observation of persons in an industrial environment , data are continuously derived therefrom as a function of the current shape and position of the virtual body model and are correlated with the data of a database . in this case , the database contains a plurality of data that have been determined in advance from shape and position of a body model during a plurality of movement phases describing a movement cycle of a person . in this case , in the course of the method those movement phases are regarded by the observed person as having been adopted by the observed person whenever the data derived from the current body model thereof exhibits a certain degree of similarity to the data stored in relation to this movement phase in the database . if in this case a specific sequence of movement phases stored in the database is detected , the movement cycle is then regarded as having been completely carried out by the observed person . if , however , the movement cycle is assessed as having been incompletely carried out , signaling to this effect is performed . this type of observation of a person advantageously enables the method for checking movement and work cycles to be applied in the industrial production field . by way of example , a complex manual mounting cycle is thereby checked during its execution as to whether appropriate work is carried out completely and in the correct sequence . should the observed movement cycle deviate from the expected one , this can be signaled . particularly in the case of highly complex modules such as , for example , aggregates , this type of quality inspection is substantially more effective than checking the assembly together with possible subsequent reworking , since in the latter case modules may be required to be completely or partially disassembled , and this is associated in turn with a high outlay on time and costs . a further advantageous field application of this alternative refinement of the invention is the supervision of newly trained operating staff . many mistakes arise in production when , for example , a new workforce needs to be trained immediately during a vacation . the work cycles can be observed by newly trained operating staff by means of the invention . it is then possible to advise when it is found that movement phases required within a movement cycle to be performed have not been fulfilled , thus resulting in the need to assume that a work operation has not been correctly carried out . in a particularly advantageous way , in the course of signaling a movement cycle assessed as incomplete a reference is made to at least one of the movement phases that is viewed as not having been adopted in the course of checking a correct sequence with reference to the movement cycle . in this way , it is particularly easy for the observed person to detect the mistake in his / her movement cycle or in his / her execution of the operation . on the other hand , a trainer can detect which sections of the learned activity are still found to be difficult by the trainee and possibly require additional explanation or further training . a statistical acquisition of the movement phases not detected as having been adopted can advantageously also enable problematic movement phases to be detected ergonomically within an entire movement cycle and , if appropriate , to be optimized by resetting the sequence of the movement phases , or by modifying the systems or objects to be operated to the observed person . in order to arrive at the data relating to the individual movement phases and / or the movement cycle for the sake of the database , it is obvious to obtain said data by means of a plurality of training cycles while the recorded images of the space to be observed , the person or the machine are being acquired by means of the multicamera system . alternatively or in addition , it is , however , also very well conceivable to generate the data of the database by simulating the movement cycle and the image information to be expected in this regard , doing so on a computer system . thus it also becomes advantageously possible for the observation system to be already preinitialized in the factory in parallel with the system design and its implementation by means of the data of the observation system that are determined by simulation . in a particularly advantageous way , the data volumes can be managed in the database , and the outlay on processing , can also be reduced by subjecting the image data stored therein to a transformation , in particular a main axis transformation . for this purpose , the correlation for determining the similarity of the currently acquired image data with the data of the database is performed on the basis of said transformed image data . in a particularly advantageous way , the 3d model of the person is created on the basis of 3d point data . these point data can be created by multiocular image analysis , in particular including stereo image analysis . for example , it is possible for information items related to each 3d point in space that go beyond the spatial coordinates ( x , y , z ) thereof , such as its speed or acceleration , to be obtained by the use of a stereo method ( as described in [ 28 ], for example ) based on space time features . the segmentation of a plurality of 3d point data ( 3d - point cloud ) is advantageously performed by means of a cluster method , in particular by means of agglomerative clustering . the convex envelope is subsequently determined for each extracted cluster of 3d points . simple features are first determined for each cluster , in particular its height or volume , in order to detect persons . it is then possible in this way for invalid , irrational clusters to be rejected , particularly starting from a - priori knowledge of the properties of a natural person . it is thus advantageously possible to combine neighboring clusters to form persons when the individual clusters do not overlap and the corresponding constraints with regard to shape and size are observed for the resulting overall object . 3d points are unnecessarily excluded in the previous step , in particular foot points in the vicinity of the floor or contact points with other objects , are preferably reinstated . the result of this first processing step is the persons in the scene , represented as convex envelopes of the clusters representing them . over time , the person thus detected can advantageously be tracked by tracking the convex envelope , projected onto the floor , that produces a 2d polygon , doing so by means of linear prediction and kalman filtering . an articulated 3d model of the human body can advantageously be matched to the person hypotheses thus found . it is advantageous in this case to model the body parts by interconnected cylinders . the posture of the person is given in this model as a vector of the joint angle of the model . the evaluation of a posture is preferably performed by determining the deviation between the features derived from the 3d - point cloud and the images of the scene , and the appearance of the model for a given posture , it thereby being possible to determine a probability that the given posture reproduces the measured shape of the person . a kernel - based particle filter [ 29 ] is particularly suitable as a probabilistic approach to the exploration of the search space . the detected movements of the body parts are advantageously represented by motion templates . such motion templates are here representative movement patterns that are included by 3d measurement of typical human movement cycles and delimit the space of possible joint angles and joint angle speeds of the person model . it is possible in this way to extrapolate the movements of the person in a biologically realistic fashion , particularly with the aim of detecting the risk of a collision between human and 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