METHOD FOR PROTECTING A WORKING AREA OF A MOBILE LOGISTICS ROBOT USING ADAPTIVE PROTECTIVE FIELDS

Description

[0001] The invention relates to a method for securing a work area of ​​a mobile logistics robot in changing work environments, wherein the logistics robot is controlled by a control system, and the current work environment is detected by means of a sensor system and monitored by a safety system, wherein the control system autonomously defines an intended, safe work area in a new work environment, and the safety system autonomously verifies and monitors the defined work area as a free protective field, and in the event of a protective field violation due to an object entering the free protective field, the logistics robot is automatically put into a safe state.

[0002] From DE 20 2017 103 611 U1 a device for safety control of a machine is known.

[0003] From DE 10 2015 220 495 A1 a generic method with the features of the preamble of patent claim 1 is known.

[0004] Robots are increasingly being used in industry and logistics companies to automate processes in industrial manufacturing and logistics tasks, such as order picking. Robots with arm manipulators, especially robot arms, are typically used for this purpose. One example of this is so-called articulated-arm robots.

[0005] In today's industrial automation, robotic applications of arm manipulators are generally operated in separate workspaces, which are usually designed as sensor-monitored safety cages. As a recent development, the state of the art includes the first collaborative robot concepts, in which humans and robots work in the same work environment. For safety reasons, however, the working speed of such robot concepts is severely limited. The so-called collaborative speed is typically a maximum of 250 mm / s. Furthermore, such robot concepts have very high product costs due to the need for safety-relevant force and torque sensors. Furthermore, they can often only lift very small payloads (in the low kilogram range), resulting in an unfavorable payload-to-deadweight ratio.

[0006] The majority of today's robotic solutions can be characterized as stationary robotic solutions, as the robot arm is either firmly anchored to the floor or mounted on a linear axis for movement. This results in a spatially restricted workspace, which is usually separated by a safety fence.

[0007] There are initial mobile approaches with robot arms on freely movable platforms. Examples include flat autonomous vehicles ("automated guided vehicles" or AGVs) or driverless industrial trucks, especially mobile order picking robots. However, these solutions are generally not suitable for mixed operations without spatial separation from human operators.

[0008] As a variation of permanently installed safety fences, initial approaches to virtual safety fences are emerging. These fences monitor the area around the robot using suitable sensors (e.g., laser scanners). If the protective field defined by the virtual safety fence is violated, the robot is safely restricted or shut down.

[0009] The spatial separation of robots and humans creates a barrier to the use of collaborative operating concepts involving human-robot collaboration. Mixed operation in areas used concurrently by humans and robots is often not possible, even with mobile robotic units mounted on moving platforms, for example. Concepts with application-adapted kinematics, in which hazard avoidance is achieved through the design of the robot housing, severely limit the design flexibility of the kinematics.

[0010] As a result of these obstacles, the existing collaborative robot concepts, due to their characteristics, have very limited fields of application. Consequently, they have achieved only extremely low market penetration to date.

[0011] The implementation of collaborative concepts is particularly challenging for logistics robots, especially autonomous industrial trucks with robotic arms for load handling, such as mobile order picking robots, because logistics robots are expected to move freely within a logistics area, such as a warehouse. In doing so, they constantly encounter completely new work environments that must be safeguarded.

[0012] The object of the present invention is to design a method of the type mentioned above in such a way that safe operation of a mobile, freely movable logistics robot is possible even in changing working environments in mixed operation with humans.

[0013] The invention is defined in claim 1.

[0014] The method according to the invention is thus capable of autonomously detecting a safe protective field area for a new work environment and having it monitored by the safety system. Unlike conventional, permanently installed safety fences and fixed virtual safety fences, the adaptive protective fields according to the invention can be continuously adapted to different work environments.

[0015] The control system can pass a mathematical description of the defined working area to the safety system.

[0016] The advantage here is that the logistics robot's electronic control system itself doesn't need to be secure. Therefore, a conventional robot arm control system can be used, for example. Protection is provided by the safety system, which can be designed as a separate electronic safety control system.

[0017] Ideally, the non-safety control system scans the work environment using sensors and defines the intended safe work area. The non-safety control system then transfers the intended safe work area as a mathematical description (preferably as a polygon) to the safety system, which adopts this definition for its safety sensors, preferably designed as scanners. These sensors can also be the same as those used by the non-safety control system to scan the work environment. The safety system confirms that the protective field is clear (i.e., not occupied).

[0018] The control system selects the protective field that covers the intended safe working area from a predefined set of protective fields.

[0019] Here, too, the non-safety-related control system scans the work environment using sensors and selects from the predefined set of protective fields the protective field that covers the intended safe work area and appropriately fulfills the detected contour of the intended safe work area. The non-safety-related control system then transfers the intended safe work area to the safety system, which adopts this definition for its safety sensors, preferably designed as scanners. These can also be the same sensors used when the non-safety-related control system scans the work environment. The safety system confirms that the protective field is clear (i.e., not occupied).

[0020] A non-safety-related control system can also be used for this purpose. The non-safety-related control system selects the protective field from a predefined set of protective fields that appropriately matches the detected contour of the intended work area. The contour of the protective fields can be arbitrary. Without loss of generality, rectangular protective fields can be assumed, in particular.

[0021] The approach outlined above specifically envisions a control system consisting of a non-safe control system, such as a robotics controller, and a (monitoring) safety system. This division is expedient because safe control systems generally have a very limited range of functions and thus cannot be mapped to more complex algorithms.

[0022] The variant presented below reduces the algorithmic complexity so that the method according to the invention can also be implemented on a simpler structured, safe control system.

[0023] Instead of scanning the work environment to define a suitable protective field, the simplification provides that a fixed set of protective fields is iteratively applied by the safety system to the changing work environment.

[0024] Accordingly, the invention relates to a method in which the control system iteratively applies a predefined set of protective fields to the working environment using the following algorithm: 1. Selection of a small protective field i, 2. Verification by the safety system as to whether the protective field i is free, 2.1 if verification as a free protective field i: Continuation with step 3, 2.2 if verification as an occupied protective field: Abort, 3. Selection of the next larger protective field i, 4. Continuation with step 2, 5. Definition of the largest possible protective field as the protective field i-1 last verified as a free protective field.

[0025] For practical purposes, the predefined set of protective fields comprises rectangular protective fields. However, depending on the nature of the work environment, it can also include other suitable shaped protective fields.

[0026] According to the invention, the free protective field is placed so close to a limiting contour of the working area that no person can stay in the space between them.

[0027] The invention therefore provides for the protective field to be placed very close to the limiting contour. This leaves only a small unmonitored area. According to existing standards, the unmonitored area must be selected so that no person can be present within it. The invention fulfills this requirement by defining the adaptive protective field in such a way that the unmonitored protected area remains below the limit specified in the standard.

[0028] The free protective field is preferably placed so close to a limiting contour of the working area that a distance of no more than 10 cm remains between the free protective field and the limiting contour.

[0029] The method according to the invention can be used to create and verify a continuous, gap-free protective field that can be defined by a curve, preferably defined by a polygon. In a further embodiment of the invention, several free protective fields are combined. This creates a non-continuous protective field that can therefore also contain gaps.

[0030] In a practical embodiment of the invention, the control system defines the intended, safe working area by evaluating the sensor data. For this purpose, at least one sensor configured as a scanner scans the work environment. A laser scanner is expediently used as the sensor.

[0031] A preferred application of the invention provides that a mobile, freely movable robotic vehicle, in particular an autonomous industrial truck, with at least one robot arm for load handling in a changing working environment is used as the logistics robot, wherein the control system controls at least the robot arm.

[0032] It is advantageous to use a non-safe control system as the control system, the control measures of which are monitored by the safety system.

[0033] Another expedient variant of the invention provides that a safe control system is used as the control system, into which the safety system is integrated.

[0034] The invention offers a number of advantages:

[0035] Working areas can be accessed without fixed protective field separation.

[0036] In addition, the working speed can be increased because the robot can be moved at "non-collaborative" speeds. Furthermore, increased payloads can be handled because permanent force and torque monitoring of the robot is not necessary, allowing larger payloads to be moved at increased speeds that exceed the monitoring limits. Sensor costs can also be reduced because collision monitoring by robot-mounted sensors is no longer necessary. Finally, the cost of the robot arm can also be reduced because standard industrial robots can be used instead of costly collaborative robots.

[0037] Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiments shown in the schematic figures. Figure 1 shows the definition of a protective field in an adaptively secured work environment, Figure 2 shows a set of predefined protective fields in an adaptively secured work environment, and Figure 3 shows the selection of the maximum unoccupied protective fields for securing the robot's work environment.

[0038] In Figure 1 The definition of a protective field S in an adaptively secured working environment A is shown. In this example, the protective field S is defined by a polygon S. For this purpose, a non-safe control system of the Figure 1 not shown logistics robot uses sensors to measure the working environment A and defines the intended, safe working area B. As shown in the Figure 1As shown, a work area B is selected that is not occupied by objects O, in this case pallets O. The non-safe control system then transfers the intended safe work area B as a mathematical description (here as a polygon S) to a safety system, which adopts this definition for its safety sensors, particularly those designed as scanners. The safety system confirms that the protective field S is free (not occupied).

[0039] In Figure 2 A set of predefined protective fields 1, 2, 3, 4 is shown. The protective fields 1, 2, 3, 4 have, for example, the shape of rectangles. For this purpose, a non-safe control system of the Figure 2not shown logistics robot with the help of sensors the working environment A and defines the intended, safe working area B. The protective fields 1, 2, 4 are free, i.e. not occupied, while the protective field 3 is occupied by objects O, in this case by pallets O. The non-safe control system of the Figure 2 The logistics robot (not shown) selects from the predefined set of protective fields 1, 2, 3, 4 those protective fields 1, 2, 4 that appropriately fulfill the detected contour of the intended work area B. The non-safe control system then transfers the unoccupied protective fields 1, 2, 4 to a safety system, which takes them over for its safety sensors, which are specifically designed as scanners. The safety system confirms that the protective fields 1, 2, 4 are free (not occupied).

[0040] The Figure 3shows how the maximum, unoccupied protective fields 1, 4 are selected using an iterative procedure. The control system of the Figure 3 not shown logistics robot iteratively applies a predefined set of protective fields to the working environment A. In this example, this is the same set of protective fields 1, 2, 3, 4 as in Figure 2 , where Figure 3 only the result of the iterative procedure is shown. First, a small protective field is selected. The safety system verifies whether the protective field is free. If so, the next larger protective field is selected. This procedure continues until the largest possible protective field is defined as the protective field last verified as free. In this example, these are protective fields 1 and 4, which are not occupied by objects O, in this case the pallets O.

Claims

1. Method for safeguarding the work area (B) of a mobile logistics robot in changing work environments (A), wherein the logistics robot is controlled by a control system, and the current work environment (A) is detected by means of a sensor system and is monitored by a safety system, wherein the control system autonomously defines an intended, safe work area (B) in a new work environment (A), and the safety system autonomously verifies the defined work area (B) as a free protection zone (S, 1, 2, 3, 4) and monitors it, and, in the event of a breach of the protection zone by an object (O) entering the free protection zone (S, 1, 2, 3, 4), the logistics robot is automatically moved to a safe state, characterized in that the control system iteratively applies a predefined set of protection zones (S, 1, 2, 3, 4) to the work environment (A), wherein the following algorithm is used: 1) selection of a small protection zone i, 2) verification by the safety system as to whether the protection zone i is free, 2a) upon verification as a free protection zone i: continue with step 3), 2b) upon verification as an occupied protection zone: abort, 3) selection of a next larger protection zone i, 4) continue with step 2), 5) definition of the largest possible protection zone as the protection zone i-1 last verified as a free protection zone, and in that the free protection zone (S, 1, 2, 3, 4) is placed so close to a delimiting contour of the work area (B) that a person cannot fit in the gap.

2. Method according to Claim 1, characterized in that the predefined set of protection zones (S, 1, 2, 3, 4) comprises rectangular protection zones (S, 1, 2, 3, 4).

3. Method according to Claim 1 or 2, characterized in that the free protection zone (S, 1, 2, 3, 4) is placed so close to a delimiting contour of the work area (B) that a distance of no more than 10 cm remains between the free protection zone (S, 1, 2, 3, 4) and the delimiting contour.

4. Method according to any of Claims 1 to 3, characterized in that several free protection zones (S, 1, 2, 3, 4) are combined.

5. Method according to any of Claims 1 to 4, characterized in that the control system defines the intended, safe work area (B) by evaluating the sensor data.

6. Method according to any of Claims 1 to 5, characterized in that at least one sensor configured as a scanner scans the work environment (A).

7. Method according to Claim 6, characterized in that a laser scanner is used as the sensor.

8. Method according to any of Claims 1 to 7, characterized in that a mobile robotic vehicle, in particular an autonomous industrial truck, having at least one robot arm for load handling in a changing work environment (A) is used as the logistics robot, wherein the control system controls at least the robot arm.

9. Method according to any of Claims 1 to 8, characterized in that a non-safe control system is used as the control system, the control measures of the non-safe control system being monitored by the safety system.

10. Method according to any of Claims 1 to 8, characterized in that a safe control system is used as the control system, the safety system being integrated into the safe control system.