Particle-Based Mechanical Hazard Determination for a Machine Safety System

Abstract

A computer-implemented method for determining a parameter of a safety configuration of a safety system for a machine includes providing a virtual model of the machine in a virtual environment. The method includes simulating a scattering of particles from the virtual model of the machine and acquiring simulation data. The method includes determining spin changes of the particles, each associated with a location at the time of the spin change. The method includes filtering the determined spin changes according to a set of filter criteria. According to a first filter criterion, filtering is performed for ones of the spin changes that are greater than or equal to a defined threshold value. The method includes determining mechanical hazard locations based on the locations that are associated with the filtered spin changes. The method includes determining the parameter of the safety configuration based on the determined mechanical hazard locations.

Claims

1. A computer-implemented method for determining a parameter of a safety configuration of a safety system for a machine, the method comprising: providing a virtual model of the machine in a virtual environment; simulating a scattering of a set of particles from the virtual model of the machine in the virtual environment, wherein simulation data of the set of particles is acquired during the simulation; determining spin changes of a subset of particles of the set of particles based on the simulation data, wherein, for each particle of the subset of particles, the spin change is associated with a location of the particle at a time of the spin change; filtering the determined spin changes according to a set of filter criteria, wherein according to a first filter criterion of the set of filter criteria, filtering is performed for ones of the spin changes that are greater than or equal to a defined threshold value; determining mechanical hazard locations based on the locations that are associated with the filtered spin changes; and determining the parameter of the safety configuration based on the determined mechanical hazard locations.

2. The method of claim 1 wherein the set of particles includes at least 1000 particles.

3. The method of claim 1 wherein the set of particles includes at least 10,000 particles.

4. The method of claim 1 wherein the set of particles includes at least 100,000 particles.

5. The method of claim 1 wherein each of the particles has a size of 1 mm to 1000 mm.

6. The method of claim 1 wherein each of the particles has a size of 5 mm to 600 mm.

7. The method of claim 1 wherein each of the particles has a size of 50 mm.

8. The method of claim 1 wherein simulating the scattering includes simultaneously scattering a certain number of the set of particles at the virtual model of the machine.

9. The method of claim 8 wherein the simulating the scattering includes simulating collisions of ones of the set of particles with each other.

10. The method of claim 1 wherein: the simulating the scattering includes emitting the set of particles inwardly from a sphere; and the sphere is arranged in the virtual environment so that it surrounds the virtual model of the machine.

11. The method of claim 1 wherein according to a second filter criterion of the set of filter criteria, filtering is performed for ones of the spin changes whose associated locations in the virtual environment are within a defined vicinity of the virtual model.

12. The method of claim 1 wherein: determining the spin changes includes generating a spin map based on the determined spin changes and the locations associated therewith; the filtering includes filtering the spin map to create a filtered spin map; and the mechanical hazard locations of the machine are determined based on the filtered spin map.

13. The method of claim 1 wherein the parameter of the safety configuration includes an arrangement of at least one of: a protection device of the safety system; a safety zone around the determined mechanical hazard locations; and a safety distance from the determined mechanical hazard locations.

14. The method of claim 1 wherein the parameter of the safety configuration is a configuration of at least one of: a protection device of the safety system; a safety zone around the determined mechanical hazard locations; and a safety distance from the determined mechanical hazard locations.

15. A method comprising: performing the method of claim 1 to determine the parameter of the safety configuration of the safety system for the machine; and setting up the safety system based on the safety configuration.

16. The method of claim 15 wherein setting up the safety system includes arranging a protection device of the safety system based on the safety configuration.

17. The method of claim 15 wherein setting up the safety system includes setting a configuration of a protection device of the safety system based on the safety configuration.

18. The method of claim 15 wherein setting up the safety system includes setting at least one of a safety zone and a safety distance based on the safety configuration.

19. The method of claim 18 wherein the safety system includes a protection device configured to monitor at least one of the safety zone and the safety distance.

20. A non-transitory computer-readable medium comprising instructions to be executed by at least one processor, the instructions including: providing a virtual model of a machine in a virtual environment; simulating a scattering of a set of particles from the virtual model of the machine in the virtual environment, wherein simulation data of the set of particles is acquired during the simulation; determining spin changes of a subset of particles of the set of particles based on the simulation data, wherein, for each particle of the subset of particles, the spin change is associated with a location of the particle at a time of the spin change; filtering the determined spin changes according to a set of filter criteria, wherein according to a first filter criterion of the set of filter criteria, filtering is performed for ones of the spin changes that are greater than or equal to a defined threshold value; determining mechanical hazard locations based on the locations that are associated with the filtered spin changes; and determining a parameter of a safety configuration of a safety system of the machine based on the determined mechanical hazard locations.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Embodiments of the invention are shown in the drawings and are explained in more detail in the following description.

[0067] FIG. 1 shows a schematic view of a machine and a safety system for securing the machine.

[0068] FIGS. 2A and 2B show two example views of arrangements of a protection device for the securing or monitoring of a hazard location.

[0069] FIG. 3 shows a schematic illustration of an embodiment of a method for determining at least one parameter of a safety configuration of a safety system for a machine.

[0070] FIG. 4 shows a schematic illustration of an embodiment of a method for setting a safety system for a machine.

[0071] FIG. 5 shows an example illustration of a collision of a ball with a plane surface.

[0072] FIG. 6 shows an example illustration of a collision of a ball with a curved surface.

[0073] FIG. 7 shows an example illustration of a simulation of the scattering of particles on a test body.

[0074] FIG. 8 shows an illustration of a spin map of the simulation from FIG. 7.

[0075] FIG. 9 shows an example illustration of a simulation of the scattering of particles on a machine.

[0076] FIG. 10 shows an illustration of a filtered spin map of the simulation from FIG. 9.

[0077] FIG. 11 shows an illustration of a more filtered spin map of the simulation from FIG. 9.

DETAILED DESCRIPTION

[0078] FIG. 1 shows a machine 10 and a safety system 12. The machine 10 comprises mechanical hazard locations 18, such as sharp edges or spikes. The safety system 12 serves to safeguard/protect the machine 10, for example, to secure the mechanical hazard locations 18. The safety system 12 comprises one or more protection devices 14, 16. The protection devices 14, 16 may be physical protection devices 14 (for example barriers, edge protectors, markers, etc.) and/or sensory protection devices 16 (for example sensors, cameras, etc.). By means of the protection devices 14, 16, the mechanical hazard locations 18 may be secured.

[0079] FIGS. 2A and 2B show two examples of securing a mechanical hazard location 18 by means of a protection device 14, 16. These examples serve as examples of a safety configuration of the safety system 12. The safety configuration defines an arrangement and/or configuration of protection devices 14, 16 of the safety system 12.

[0080] In the first example (FIG. 2A), a physical protection device 14—for example a barrier—is arranged at a certain safety distance 22 from a mechanical hazard location 18 of the machine 10. The physical protective device 14 impedes or prevents access to the mechanical hazard location 18.

[0081] In the second example (FIG. 2B), a sensory protection device 16—for example a camera or an optical sensor—is arranged such that it monitors a safety zone 20 around a mechanical hazard location 18 of the machine 10. The sensory protection device 16 is configured to detect when a human enters the safety zone 20 and/or is present in the safety zone 20. If the sensory protection device 16 detects this, an alarm may be triggered, for example.

[0082] FIG. 3 shows an embodiment of a method 30 for determining at least one parameter of a safety configuration of the safety system 12 for the machine 10. The method 30 may be performed in a computer-based manner. For example, the steps of the method 30 may be performed using a computer. Therefore, the method 30 is a computer-implemented method.

[0083] In a first step 32 of method 30, a virtual model of the machine 10 is provided in a virtual environment.

[0084] In a further step 34 of the method 30, a scattering of one or more particles from the virtual model of the machine 10 is simulated in the virtual environment, wherein simulation data of the particles are acquired during the simulation. As simulation data, a location and a spin of each particle may be acquired at a plurality of successive times over the duration of the simulation.

[0085] The number of particles can be greater than 1000, greater than 10,000 or 30,000, or greater than 100,000. The particles can comprise a particle size of 1 mm to 1000 mm, 5 mm to 600 mm, or 50 mm.

[0086] To simulate the scattering, a certain number of the particles may be scattered simultaneously on the virtual model of the machine, for example, wherein the particles may collide with each other during simulating the scattering.

[0087] Further, to simulate the scattering, the particles, for example, the certain number of particles, may be emitted inwardly from an emission sphere, wherein the emission sphere is arranged in the virtual environment such that it surrounds the virtual model of the machine 10. Additionally, a reflection sphere may also be provided in the virtual environment, which can surround the emission sphere. During the simulation, the reflection sphere reflects the particles, which collide with the reflection sphere from the inside, back to the inside.

[0088] In a further step 36 of the method 30, spin changes of the particles are determined based on the simulation data, wherein each determined spin change is associated with a location of the corresponding particle at the time of the spin change. For example, a spin map may be generated based on the determined spin changes and the associated locations.

[0089] In a further step 38 of the method 30, the determined spin changes are filtered according to one or more filter criteria. According to a first filter criterion of the filter criteria, filtering may be performed for spin changes that are greater than or equal to a defined threshold value. According to a second filter criterion of the filter criteria, filtering may be performed for spin changes whose associated locations in the virtual environment are at or near the virtual model. For example, in the step of filtering 38, the spin map may be filtered.

[0090] In a further step 40 of method 30, mechanical hazard locations are determined based on the locations associated with the filtered spin changes. For example, mechanical hazard locations may be determined based on the filtered spin map.

[0091] In a further step 42 of method 30, the at least one parameter of the safety configuration is determined based on the determined mechanical hazard locations. For example, a plurality of the safety configuration may also be determined based on the determined mechanical hazard locations. The at least one parameter of the safety configuration defines an arrangement and/or configuration of a protection device 14, 16 of the safety system 12 and/or an arrangement of a safety zone 20 around the determined mechanical hazard locations and/or a safety distance 22 from the determined mechanical hazard locations.

[0092] FIG. 4 shows an embodiment of the new method 50 for setting up the safety system 12 for the machine 10.

[0093] In a first step 52 of the method 50, at least one parameter of a safety configuration of the safety system 12 for the machine 10 is determined. The determination of the at least one parameter of the safety configuration of the safety system 12 for the machine 10 may be performed using the method 30 of FIG. 3.

[0094] In a further step 54 of the method 50, the safety system 12 is set up based on the safety configuration that is defined by means of the at least one, determined parameter. In setting up the security system 12, a protection device 14, 16 of the security system 12 may be arranged and/or configured based on the security configuration. Further, in setting up the safety system 12, a safety zone 20 or a safety distance 22 may be set up based on the safety configuration, wherein the safety zone 20 or the safety distance 22 is monitored or secured by means of a protection device 14, 16 of the safety system 12.

[0095] FIGS. 5 to 8 describe the operation of the particle spin method on which the new method is based.

[0096] First of all, two thought experiments are considered in FIGS. 5 and 6. One is in an idealized environment (gravity present) but no damping is considered (concretely: no friction, no air resistance).

[0097] First, in FIG. 5, a collision of a ball 100 (a sphere) with a flat surface 102 (a flat floor) is considered. One is in a room, with a flat floor. Now, a ball is dropped straight down without spin. The ball will now return to where it was dropped. In this process, the ball will hit the ground with the frontmost point in the direction of flight first. This point may be called the point of impact and is designated by the reference sign 104 in FIG. 5. With this collision, the ball does not get any spin or twist after the collision.

[0098] Second, in FIG. 6, a collision of a ball 110 (a sphere) with a curved surface 112 (an undulating floor) is considered. For example, in FIG. 5, the same experiment as in FIG. 5 is repeated, but now with an undulating floor instead of a flat floor. Now the case occurs that the ball 110 no longer hits with the foremost point in the direction of flight, but with an arbitrary other point 114, which is located on the lower half of the ball 110, 110′, 110″. For better illustration, this is shown in FIG. 6 with several balls 110, 110′, 110″ which come into contact with the curved surface 112 at different impact points 114, 114′, 114″ during impact.

[0099] The particle spin method makes use of this characteristic, especially for edges it is statistically more likely that a particle does not hit straight and thus gets a spin. For example, the sharper the edge or spike of the body with which the particle collides, the greater is the resulting spin change.

[0100] In FIG. 7, the particle spin method is demonstrated using an example of a test body 120 that comprises a conical shape. For example, the test body 120 is a cone. In the particle spin method, particles 122 are scattered from the test body 120, and spin changes of the particles during the scattering are analyzed.

[0101] For this purpose, a virtual environment, i.e. a simulation environment, is initially provided. The virtual environment may be generated, for example, by means of a graphics engine. For example, the computer program Blender may be used for this purpose to generate the virtual environment as well as objects in this virtual environment and to simulate their movement. The virtual environment provides a three-dimensional virtual space, which may be described using Cartesian coordinates, for example.

[0102] In the virtual environment, a model of the test body 120 is initially generated or provided. The center of mass or the center of the test body 120 can be arranged in the origin of the virtual environment. In the virtual environment, an emission sphere 124 is then arranged around the test body (for example, around the origin of the virtual environment). Additionally, a reflection sphere may be arranged around the test body, which is at least as great as the emission sphere 124 and surrounds or coincides with the emission sphere 124.

[0103] An attractive force field (gravitational field) may be generated or simulated at the center or center of mass of the test body 120 or at the origin of the virtual environment. Alternatively, an external repulsive force field may be generated that is located on either the emission sphere or the reflection sphere or surrounds both spheres. By means of the force field, the particles 122 are accelerated towards the test body 120.

[0104] At the start of the simulation, the particles 122 are generated on the emission sphere 124. The generation locations are randomly distributed or uniformly distributed over the entire emission sphere 124. The number of particles may be, for example, 10,000 to 30,000. The particle size may be, for example, 5 cm. The appropriate particle number may vary greatly depending on the complexity of the test body. The particles can be round and can have a mass. Further, the particles have a surface roughness, which may also be called stickiness.

[0105] To simulate the scattering, the movement of the particles is simulated after their generation, for example in discrete simulation steps. Each simulation step corresponds to a time interval. The simulation steps may also be referred to as time steps. Each simulation step may thus be associated with a time during the simulation. The simulation can comprise at least 1,000 simulation steps. For each simulation step (i.e. for each time), at least the location (e.g. three variables) and the spin (e.g. three or four variables) of each particle are acquired as simulation data. For example, the simulation data are acquired for the entire duration of the simulation (i.e. for all simulation steps). The acquired simulation data can be stored during the simulation. The stored simulation data is then available for further analysis (for example, for determining the spin changes and the mechanical hazard locations).

[0106] The particles can be emitted from the surface of the emission sphere inwardly, for example, in the normal direction to the surface, at a certain velocity during their generation. During the simulation, the particles 122 can collide with each other as well as with the virtual model of the test body 120 as well as with the reflection sphere 124. In this process, the particles do not collide with their center of mass/center, but with their outer shell/surface. In this way, the surface of the test body 120 is scanned with the particles during the simulation. When scattering at the test body, the particles can change their spin.

[0107] Based on the simulation data acquired during the simulation, it can then be determined if and when the spin of a particle changed during the simulation and if so, how great the spin change is. In this way, all spin changes of the particles that occurred during the simulation are determined. A spin map may then be generated based on the determined spin changes.

[0108] Next, the spin changes or the spin map are filtered. On the one hand, it may be filtered for spin changes that occurred in a certain, limited area around the test body (i.e. at or near the test body). Spin changes that are not caused by a collision with the test body are filtered out. Further, it may be filtered for spin changes that or whose absolute values are greater than a certain threshold value. In this way, small spin changes that are not caused by collisions with edges or spikes can be filtered out.

[0109] In FIG. 8, a spin map with spin changes on the surface of the test body (cone) from the simulation in FIG. 7 is shown. The spin map may also be referred to as a “spin heat map”. For example, in the spin map of FIG. 8, it can be seen that the spike as well as the bottom edge of the cone comprise higher spin changes than the rest of the cone. The location of a high spin change thus corresponds (at least with high probability) to the location of a spike or edge, i.e. a mechanical hazard location, of the test body. If the threshold value for filtering is increased accordingly, only spin changes at the spike and at the lower edge of the cone remain.

[0110] As described above, the spin map is used to analyze the spin change of the particles between two times. The particles all have random flight directions and also collide with each other. The idea of a frictionless ball pool, where each ball has a velocity, is very appropriate. In this method, the particle size is also freely adjustable, so one may also specify whether a particle is large enough to reach a certain location. In other words, the particle size may be adapted to the dimensions of parts of the human body (e.g. arm, hand, finger). Thus, indirectly, one also makes a reachability analysis by looking at the locations where spin changes occur and those where they do not.

[0111] Based on the filtered spin map, the location of mechanical hazard locations such as edges and spikes may thus be determined. For example, the locations of the filtered spin changes correspond to the location of mechanical hazard locations of the machine.

[0112] In FIGS. 9-11, example simulation of the scattering of particles from a machine is shown. In FIG. 9, a model of the machine is arranged in a virtual environment. In this example, the machine comprises a conveyor belt and a robotic arm adjacent to a conveyor belt.

[0113] In FIG. 10, a spin map of the simulation from FIG. 9 is shown. The spin changes were filtered using a threshold method, wherein a small threshold value was used. The spin map of FIG. 10 comprises spin changes at locations of most of the edges and spikes of the machine.

[0114] In FIG. 11, a spin map of the simulation from FIG. 9 is shown, wherein the spin changes were previously filtered using a greater threshold value than in FIG. 10. In this way, in the spin map, spin changes are only shown at locations that are located at sharper edges or spikes of the machine.

[0115] Based on the filtered spin map, the location of mechanical hazard locations may be determined. By means of the threshold value used for filtering, the sensitivity may be adjusted. The higher the threshold value, the sharper an edge must be to be detected.

[0116] The term non-transitory computer-readable medium does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave). Non-limiting examples of a non-transitory computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

[0117] The phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” Overall, the present invention is not limited by the examples of implementation presented here, but is defined by the following claims.