DEVICE AND METHOD FOR DETERMINING, IN AT LEAST THREE SPATIAL DIRECTIONS, A FORCE ACTING ON A BODY, AND METHOD FOR CONTROLLING THE MOVEMENT OFA BODY

Abstract

A device for determining, in at least three spatial directions, a force acting on a body includes at least one sensor element for attaching to the surface of the body, which element includes at least three individual sensor elements, each individual sensor element being designed to determine an individual force in one direction, or which includes at least one individual sensor element which is used to determine an individual force in three spatial directions, and an evaluation/control unit which records the individual force determined by each individual sensor element and is designed to calculate the force acting on the sensor element in at least three spatial directions by projecting the individual forces onto a virtual point of the sensor element. A method for determining a force acting on a body in at least three spatial directions and a method for controlling the movement of a body is disclosed.

Claims

1. A device for determining, in at least three spatial directions (Fx, Fy, Fz, Mx, My, Mz), a force acting on a body (3), in particular a manipulator, comprising at least one sensor element (1, 2) for attaching to the surface (3.1) of the body (3), which comprises at least three individual sensor elements (1.3), each individual sensor element (1.3) being designed to determine an individual force in one direction, or which comprises at least one individual sensor element (1.3) which is designed to determine an individual force in three spatial directions, and an evaluation/control unit (6) which records the individual force determined by each individual sensor element (1.3) and is designed to measure the force acting on the sensor element (1, 2) in at least three spatial directions (Fx, Fy, Fz, Mx, My, Mz) by projecting the individual forces onto a virtual point (1.2, 2.2) of the sensor element (1, 2).

2. The device according to claim 1, characterized in that each sensor element (1, 2) comprises a plurality of, preferably at least 15, particularly preferably at least 20, individual sensor elements (1.3).

3. The device according to claim 1, characterized in that the individual sensor elements (1.3) are arranged in a grid or a polar arrangement.

4. The device according to claim 1, characterized in that the individual sensor elements (1.3) of each sensor element (1, 2) has at least two groups of individual sensor elements (1.3′, 1.3″) which can be evaluated independently of one another.

5. The device according to claim 1, characterized in that the individual sensor elements (1.3′, 1.3″) of each group are each arranged in a grid or a polar arrangement, the grids or polar arrangements preferably being arranged in an interlocking manner and are designed, for example, in the manner of a chessboard.

6. The device according to claim 1, characterized in that the device comprises at least two sensor elements (1, 2) which are preferably arranged at a distance (A) from one another, particularly preferably on two opposite sides of the surface (3.1) of the body (3).

7. The device according to claim 6, characterized in that the sensor elements (1, 2) can be evaluated independently of one another.

8. The device according to claim 1, characterized in that the sensor element (1) has a cover (1.4) which is freely mounted relative to the sensor element (1).

9. The device according to claim 1, characterized in that the sensor element (1, 2) is made of a flexible material which can be applied to the body (3) in particular in the manner of a skin.

10. The device according to characterized in that the evaluation/control unit (6) comprises a controller (5) into which the force acting on the body (3) can be introduced as an actual value (5.1).

11. A body (3), in particular a manipulator, preferably an industrial robot or cobot, with a device (10) according to claim 1, the at least one sensor element (1, 2), preferably the at least two sensor elements (1, 2), being arranged on the surface (3.1) of the body (3).

12. The body according to claim 11, characterized in that a large number of sensor elements (1, 2) are arranged on the surface (3.1) of the body (3) and these cover in particular a large part of the surface (3.1), preferably the entire surface (3.1), of the body (3) cover, the sensor elements (1, 2) preferably being made of a flexible material which can be applied in particular in the manner of a skin on the body (3).

13. A method for determining, in at least three spatial directions (Fx, Fy, Fz, Mx, My, Mz), a force acting on a body (3), in particular a manipulator, comprising at least one sensor element (1, 2) mounted on the surface (3.1) of the body (3), which element comprises at least three individual sensor elements (1.3), each individual sensor element (1.3) being designed to determine an individual force in one direction, or which comprises at least one individual sensor element (1.3) which is designed to determine an individual force in three spatial directions is, and an evaluation/control unit (6), with the steps: determining each individual force acting on each individual sensor element (1.3), and calculating the force acting on the sensor element (1, 2) in at least three spatial directions (Fx, Fy, Fz, Mx, My, Mz) by projecting the individual forces onto a virtual point (1.2, 2.2) of the sensor element (1, 2).

14. The method for determining a force acting on a body according to claim 13, characterized in that at least two sensor elements (1, 2) are arranged on the surface (3.1) of the body (3) at a distance (A) from one another, the following steps being carried out: determining each individual force acting on each individual sensor element (1.3) for each sensor element (1, 2), calculating the force acting on the sensor element (1, 2) in at least three spatial directions (Fx, Fy, Fz, Mx, My, Mz) by projecting the individual forces onto a virtual point (1.2, 2.2) of the sensor element (1, 2) for each sensor element (1, 2), and calculating the forces (Fx, Fy, Fz) and torques (Mx, My, Mz) acting on the body (3) by projecting the forces acting on the sensor elements (1, 2) onto a virtual point (4) of the body (3), which is in particular spaced apart from the sensor elements (1, 2).

15. The method according to claim 13, characterized in that the force acting on the body (3) is determined independently of one another by means of two groups of individual sensor elements (1.3′, 1.3″).

16. A method for controlling the movement of a body (3), in particular a manipulator, with the steps: determining the force acting on the body (3) using a method according claim 13, introducing the force acting on the body (3) into a controller (5) as an actual value (5.1), comparing the actual value (5.1) with a target value (5.6) of the controller (5), and determining a manipulated variable (5.2) for movement control in order to achieve the target value (5.6).

17. The method for controlling the movement of a body according to claim 16, characterized in that disturbance variables (5.5) are taken into account in the controller (5).

18. A method for controlling a body (3), in particular a manipulator, with the steps: determining the force acting on the body (3) using a method according claim 13, comparing the determined force (F) with a predetermined minimum force value (G1) and/or a maximum force value (G2), and releasing the movement of the body (3) if the determined force (F) is greater than the minimum force value (G1) and/or less than the maximum force value (G2).

19. A method for controlling a body (3), in particular a manipulator, with the steps: determining the force acting on the body (3) using a method according claim 13, as a function of time, and recognizing patterns of the force acting on the body (3) for input and/or control commands.

Description

[0044] The invention is explained in detail using the exemplary embodiments illustrated in the following figures, in which:

[0045] FIG. 1 is a schematic perspective representation of an embodiment of a device according to the invention with two sensor elements,

[0046] FIG. 2 is a schematic representation of a controller of the device according to FIG. 1,

[0047] FIG. 3 is a schematic representation of release switching stages for the device according to FIG. 1,

[0048] FIG. 4 is a schematic perspective view of an alternative embodiment of a device according to the invention with a sensor element, and

[0049] FIG. 5 is a schematic representation of a pattern of the force acting on the body 3 for a control command.

[0050] FIG. 1 is a schematic perspective representation of an embodiment of a device 10 according to the invention for determining, in at least three spatial directions Fx, Fy, Fz, a force F acting on a body 3 with at least one, in the present embodiment with two sensor elements 1, 2 for attaching to a surface 3.1 of the body 3, and an evaluation/control unit 6.

[0051] The body 3 shown can be a partial segment, for example an arm or a section of an arm, of a manipulator, for example an industrial robot or a cobot. The body 3 can have any conceivable shape and, of course, also have components that can be moved relative to one another. The body 7 comprises a drive unit 7, by means of which the body 7 can be moved either relative to other components or relative to the ground. For example, by means of the drive unit 7, the body 3 designed as a sub-segment of an arm of a manipulator can be rotated and/or tilted relative to a further sub-segment of the arm of the manipulator. The drive unit 7 can be actuated by means of the evaluation/control unit 6, which can be arranged either in or on the body 3 or can be designed as a separate unit.

[0052] The sensor elements 1, 2 each have a measuring surface 1.1, 2.1, which—as shown by way of example for the sensor element 1—comprises individual sensor elements 1.3. The individual sensor elements 1.3 are designed either to determine an individual force in one direction, generally perpendicular to the surface of the individual sensor element 1.3, or to determine an individual force in three spatial directions. When using an individual sensor element 1.3, which is designed to determine an individual force in three spatial directions, the sensor elements 1, 2 each have at least one of the individual sensor elements 1.3, preferably a plurality of individual sensor elements 1.3. When using individual sensor elements 1.3 which are designed to determine an individual force in one direction, the sensor elements 1, 2 each have at least three of the individual sensor elements 1.3, preferably a plurality individual sensor elements 1.3.

[0053] In a preferred, optional embodiment, the sensor elements 1, 2 have at least 15, for example 16 individual sensor elements 1.3 arranged in a 4×4 grid, particularly preferably at least 20, in the present exemplary embodiment 24. A larger number of individual sensor elements 1.3 can improve the resolution, regardless of whether the individual sensor element 1.3 determines the force in one or in three spatial directions.

[0054] The individual sensor elements 1.3 are preferably arranged in a grid or a polar arrangement, for example as shown in the figures in rows and columns with the same grid dimensions. In particular, it is essential to know the orientation of the individual sensor elements 1.3 relative to one another for the evaluation.

[0055] For each sensor element 1, 2, the force acting on the sensor element 1, 2 in three spatial directions Fx, Fy, Fz can be determined in such a way that a projection of the forces acting on the individual sensor elements 1.3 onto a virtual point 1.2, 2.2 of the sensor element 1, 2 is carried out, in particular by means of the evaluation/control unit 6. The virtual point 1.2, 2.2 in particular lies on the measuring surface 1.1, 2.1, for example centrally. By considering the position of one of the individual sensor elements 1.3 relative to the virtual point 1.2, 2.2 and evaluating the absolute amounts of the individual forces acting on the individual sensor elements 1.3, the force acting on the sensor element 1, 2, in particular at the virtual point 1.2, 2.2, can be determined in three spatial directions, that is, in particular the three force components Fx, Fy, Fz.

[0056] Each of the two sensor elements 1, 2 described above allows the force acting on the sensor element 1, 2 and thus also on the body 3 to be determined in three spatial directions.

[0057] In a method for determining, in at least three spatial directions, a force acting on the body 3, in particular a manipulator, with exactly one sensor element 1, 2 mounted on the surface 3.1 of the body 3, which element comprises at least three individual sensor elements 3.1, with each individual sensor element 1.3 being designed to determine an individual force in one direction, or which comprises at least one individual sensor element 1.3 which is designed to determine an individual force in three spatial directions, and an evaluation/control unit 6, the following steps can then be carried out: Firstly, each individual force acting on each individual sensor element 1.3 is determined. Then, the force acting on the sensor element 1, 2 in three spatial directions Fx, Fy, Fz is calculated by projecting the individual forces onto a virtual point 1.2, 2.2 of the sensor element 1, 2.

[0058] Through a combined evaluation of the two sensor elements 1, 2, which can be arranged on opposite sides of the surface 3.1 of the body 3, for example as shown in FIG. 1, the force acting on the body 3 can be determined in a simple manner, not only in three but in six directions in space, that is, the acting forces Fx, Fy, Fz and the acting torques Mx, My, Mz. The sensor elements 1, 2 can be arranged at a distance A from one another, with the sensor element 1 being able to have the distance a from a virtual point 4 of the body 3 and the sensor element 2 being able to have a distance b from the virtual point 4 of the body 3. The distance A preferably corresponds to the sum of the distances a and b. To determine the force acting on the body 3 in six spatial directions, the forces acting on the sensor elements 1, 2 are projected onto the virtual point 4 of the body 3, in particular by means of the evaluation/control unit 6. Since the virtual point 4 is not in the measuring surface 1.1, 2.1 of the sensor elements 1, 2, but at a distance from it, by considering the position of each of the individual sensor elements 1.3 relative to the virtual point 4 and evaluating the absolute values of the values of the individual forces acting on the individual sensor elements 1.3, in addition to the forces Fx, Fy, Fz acting in three spatial directions, the torques Mx. My, Mz acting around the axles can also be determined.

[0059] In a method for determining in at least three, preferably in six, spatial directions, a force acting on the body 3, in particular a manipulator, comprising at least two sensor elements 1, 2 spaced apart from one another on the surface 3.1 of the body 3, each of which has at least three individual sensor elements 3.1, with each individual sensor element 1.3 being designed to determine an individual force in one direction, or which each comprise at least one individual sensor element 1.3 which is designed to determine an individual force in three spatial directions, and an evaluation/control unit 6, the following steps can be carried out: Firstly, each individual force acting on each individual sensor element 1.3 is determined for each sensor element 1, 2. Then, the force acting on the sensor element 1, 2 is calculated in three spatial directions by projecting the individual forces onto a virtual point 1.2, 2.2 of the sensor element 1, 2. Finally, the forces Fx, Fy, Fz and torques Mx, My, Mz acting on the body 3 are calculated by projecting the forces acting on the sensor elements 1, 2 onto a virtual point 4 of the body 3, which is in particular spaced apart from the sensor elements 1, 2.

[0060] An alternative or additional possibility for determining the force acting on the body 3 not only in three but in six spatial directions is explained with reference to FIG. 4. The sensor element 1 shown there differs from the sensor element 1 shown in FIG. 1 in that it has a cover 1.4 that is freely mounted relative to the sensor element 1 and is arranged in particular in parallel with the measuring surface 1.2. The cover 1.4 can be fixed, for example, to the surface 1.3 of the body, but can be moved relative to the sensor element 1 and in particular to the measuring surface 1.2. A user thus grips the outer surface of the cover 1.4, but the cover 1.4 is connected to the individual sensor elements 1.3 so that the force exerted on the cover 1.4 is transmitted to the individual sensor elements 1.3 via the back of the cover 1.4. The virtual point 1.2 is at a distance from the outer surface of the cover 1.4 in the measuring surface 1.2, as a result of which not only the three force components Fx. Fy, Fz can be determined in three spatial directions, but the effective torques Mx, My, Mz as well.

[0061] In a method for determining, in at least three spatial directions, a force acting on the body 3, in particular a manipulator, with a sensor element 1 mounted on the surface 3.1 of the body 3, in particular according to FIG. 4, which element has at least one individual sensor element 1.3, which is used to determine an individual force in three spatial directions, or at least three individual sensor elements which are designed to determine an individual force in one direction, and a cover 1.4 that is freely mounted relative to the sensor element 1, and an evaluation/control unit 6, the following steps can be carried out: Firstly, each individual force acting on each individual sensor element 1.3 is determined. Then, the force acting on the sensor element 1, 2 is calculated in three spatial directions by projecting the individual forces onto a virtual point 1.2 of the sensor element 1, 2, taking into account the distance between cover 1.4 and measuring surface 1.1.

[0062] FIG. 1 shows the sensor elements 1, 2 as planar sensor elements 1, 2 which are shown tangentially to the curved surface 3.1 of the body 3 in a non-realistic way for the sake of simplicity of the drawing. The sensor elements 1, 2 preferably adapt to the surface 3.1 of the body 3. In a particularly advantageous manner, the sensor elements 1, 2 can be made of a flexible material. Advantageously, the sensor elements 1, 2 can be applied to the body 3 in the manner of an artificial, tactile skin. A large number of sensor elements 1, 2 can be arranged on the surface 3.1 of the body 3 and in particular can cover a large part of the surface 3.1, preferably the entire surface 3.1, of the body 3.

[0063] To control the movement of the body 3, a manipulated variable is preferably determined based on the force acting on the body, which the drive unit 7 converts into a corresponding movement of the body 3 in the direction of the acting force. A controller 5 is preferably provided, in particular in the evaluation/control unit 6, which is shown schematically in FIG. 2. The controller 5 is intended to carry out a subsequent movement of the body 3 in the direction of a force imbalance on the basis of the change in the force balance of the body 3. To this end, the controller 5 can comprise a controlled system 5.3 and a control device 5.4, with the control device 5.4 receiving a control difference 5.8 as an input value, which difference results from an actual value 5.1 and a target value 5.6 in a comparing element 5.7. The actual value 5.1 corresponds in particular to the force acting on body 3, which was determined using sensor elements 1, 2. The target value 5.6 can be defined, for example, by the balance of forces. As a result, the controlled system 5.3 delivers a controlled variable 5.2 which can specify the manipulated variable for the drive unit 7. Disturbance variables 5.5 can be taken into account in the controlled system 5.3. The movement of the body that is then carried out can be, for example, a linear movement or a rotary movement. The center of the movement can be placed at any point of the body 3 by a kinematic transformation, for example at the virtual point 4, but also at other points. The evaluation/control unit 6 and the drive unit 7 make it possible to determine one or more spatial directions, and therefore specific movements can be carried out in desired spatial directions.

[0064] Subsequent to each of the methods described for determining the force acting on the body 3, the forces acting on the body can then, for example, be introduced into the controller 5 as actual values 5.1, the actual values 5.1 can be compared with the target value 5.6, and a manipulated variable for movement control for achieving the target value 5.6 can be determined in order to provide a method for controlling the movement of the body 3. In this method for controlling the movement of the body 3, disturbance variables 5.5, in particular in the controlled system 5.3, can also be taken into account in the controller 5.

[0065] Data and signal transmission between all components can be wired or wireless.

[0066] In each of the calculations described, all of the individual sensor elements 1.3 can be used for the evaluation. There is also the possibility of dividing the individual sensor elements 1.3 into two groups of individual sensor elements 1.3′, 1.3″, it being possible to evaluate the group of the individual sensor elements 1.3′, which is shown in FIG. 1 without hatching for illustration purposes, independently of the group of the individual sensor elements 1.3″, which is shown in FIG. 1 with hatching for illustration purposes, for example, to allow for a redundant evaluation. The individual sensor elements 1.3′, 1.3″ in each group are preferably arranged in a grid or a polar arrangement, with the grid or polar arrangements being arranged in particular in an interlocking manner, for example in the manner of a chess board (cf. FIG. 1 or FIG. 4). If there are several sensor elements 1, 2, a separate and/or independent evaluation of each sensor element 1, 2 is also possible in order to be able to carry out an additional plausibility check and, for example, to check whether a force is applied to each of the sensor elements 1, 2 and/or to allow for further redundancy.

[0067] In each of the methods described for determining a force acting on the body 3, the force acting on the body can thus be determined independently of one another by means of two groups of individual sensor elements 1.3′, 1.3″.

[0068] Further safety-relevant functions can be implemented by suitable evaluation of the individual forces acting on the sensor elements 1, 2 and in particular on the individual sensors 1.3. Typical safety-relevant release switches for movements of the body 3, such as a dead man's switch or a confirmation switch, can have three switching stages, namely a switching stage S1, in which the switch is not actuated, a switching stage S2, in which a movement of the body 3 is released, and a switching stage S3, in which an emergency stop takes place. For this purpose, a minimum force value G1 and a maximum force value G2 can be defined as the lower and upper switching thresholds, the switching stage S1 being at a force below the minimum force value G1, the switching stage S2 being at a force between the minimum force value G1 and the maximum force value G2, and the switching stage S3 being at a force above the maximum force value G2 (see FIG. 3, in which an example of the amount F of the forces acting on the sensor elements 1, 2 are plotted as a function of time t). For example, the movement of the body 3 can be released if the amount F of the force acting on the sensor element 1, 2 is in the range of the switching stage S2 for one of the sensor elements 1, 2. The safety function is improved if, as shown in FIG. 3, the movement of body 3 is released when for both sensor elements 1, 2 the amount F of the force acting on sensor element 1, 2 is in the range of switching stage S2. In an example of a method for controlling the body 3, the force acting on the body 3 can then firstly be determined using the sensor elements 1, 2, then the determined force, in particular the amount F of the averaged force, are compared with a predefined minimum force value G1 and/or a maximum force value G2, and the movement of the body 3 is released if the determined force or the amount F of the determined force is greater than the minimum force value G1 and/or less than the maximum force value G2.

[0069] In one embodiment of the invention, patterns of the force acting on the body 3 for control commands can be stored in the evaluation/control unit 6, the patterns representing force profiles as a function of the time t. The force acting on the body 3 as a function of time t, in particular the amount F of the force acting on the body 3 as a function of time t, can be compared with the stored patterns in order to identify such patterns and subsequently execute the corresponding control command. FIG. 5 shows an example of a force profile in which the sensor element 1 is tapped twice. The force maxima occur at the times t1 and t2. If, for example, the time interval t2−t1 is less than a time difference specified in the stored pattern and the force maxima exceed a minimum limit value G1 specified in the stored pattern, the pattern can be recognized and the corresponding control command which is linked to the pattern and correspondingly stored in the evaluation/control unit can be executed, for example, the current position of the body 3, such as an arm of a manipulator, can be stored or operation of accessories attached to the body 3 such as an input field are enabled.

[0070] Therefore, in a method for controlling the body 3, in particular a manipulator, therefore, patterns of the force acting on the body 3 for input and/or control commands can be detected after determining the force acting on the body 3, in particular the amount F of the force acting on the body 3, as a function of time t.

LIST OF REFERENCE NUMERALS

[0071] 1 Sensor element [0072] 1.1 Measuring surface [0073] 1.2 Virtual point [0074] 1.3 Individual sensor element [0075] 1.3′ Individual sensor element [0076] 1.3″ Individual sensor element [0077] 1.4 Cover [0078] 2 Sensor element [0079] 1.1 Measuring surface [0080] 2.1 Virtual point [0081] 3 Body [0082] 3.1 Surface [0083] 4 Virtual point [0084] 5 Controller [0085] 5.1 Actual value [0086] 5.2 Controlled variable [0087] 5.3 Controlled system [0088] 5.4 Control device [0089] 5.5 Disturbance variable [0090] 5.6 Target value [0091] 5.7 Comparing element [0092] 5.8 Control difference [0093] 6 Evaluation/control unit [0094] 7 Drive unit [0095] 10 Device [0096] A Distance [0097] a Distance [0098] b Distance [0099] F Force [0100] Fx Force [0101] Fv Force [0102] Fz Force [0103] Mx Torque [0104] My Torque [0105] Mz Torque [0106] t Time [0107] S1 Switching stage [0108] S2 Switching stage [0109] S3 Switching stage [0110] G1 Minimum force value [0111] G2 Maximum force value