METHOD FOR DETERMINING A RELATIVE MOUNTING POSITION OF A FIRST SENSOR UNIT IN RELATION TO A SECOND SENSOR UNIT ON AN INDUSTRIAL TRUCK

Abstract

A method for determining a relative mounting position of a first sensor unit in relation to a second sensor unit on an industrial truck. The method includes placing the industrial truck in a first orientation with respect to a planar structure. The method includes detecting the planar structure using the two sensor units and determining a distance between each respective sensor unit and the planar structure. The method includes placing the industrial truck in a second orientation having at least a different angle between the longitudinal axis of the industrial truck and the planar structure. The method includes detecting the planar structure using the sensor units and determining a distance between each respective sensor unit and the planar structure. The method includes deriving an offset of the sensor units with respect to length and width directions and an angle between the sensor units with respect to a same spatial axis.

Claims

1. A method for determining a relative mounting position of a first sensor unit relation to a second sensor unit on an industrial truck, comprising: placing the industrial truck in a first orientation with respect to a planar structure, wherein the industrial truck has a length direction, a width direction, and a height direction; detecting the planar structure using the first sensor unit and the second sensor unit and determining, for each of the first sensor unit and the second sensor unit, a distance between the respective sensor unit and the planar structure in the first orientation, wherein the first sensor unit and the second sensor unit each have a respective detection field and supply respective sensor data; placing the industrial truck in a second orientation with respect to the planar structure, wherein at least an angle between the longitudinal axis of the industrial truck and the planar structure differs between the first orientation and the second orientation; detecting the planar structure using the the first sensor unit and the second sensor unit and determining, for each of the first sensor unit and the second sensor unit, a respective distance between the respective sensor unit and the planar structure in the second orientation; and deriving the offset of the first sensor unit and the second sensor unit with respect to the length direction and width direction the angle between the two sensor units the first sensor unit and the second sensor unit with respect to same spatial axis.

2. The method of claim 1, wherein one of the first sensor unit and the second sensor unit units is a laser scanner and the other of the first sensor unit and the second sensor unit is a three-dimensional (3D) area sensor .

3. The method of claim 1 , wherein the sensor data supplied by the sensor units first sensor unit and the second sensor unit is transformed and mapped in same coordinate system.

4. The method of claim 1 , further comprising performing multiple times in at least one further orientation, steps of: placing the industrial truck in a second orientation with respect to the planar structure, wherein at least an angle between the longitudinal axis of the industrial truck and the planar structure differs between the first orientation and the second orientation; and detecting the planar structure using the first sensor unit and the second sensor unit and determining, for each of the first sensor unit and the second sensor unit, a respective distance between the respective sensor unit and the planar structure in the second orientation.

5. The method of claim 1, wherein the step of deriving comprises a calculation .

6. The method of claim 4 and 5, wherein the calculation comprises performing a quadratic optimisation function.

7. The method of claim 1 , wherein, in one or more of the first orientation, the second orientation, or at least one further orientation, the planar structure lies at least partially within an overlapping area of the detection fields of the first sensor unit and the second sensor unit.

8. The method of claim 1 according , wherein the planar structure is formed substantially vertically.

9. The method of claim 1 , wherein the planar structure comprises at least two surface portions arranged at an angle to one another.

10. A system, comprising: a data processing unit which is operatively coupled to a first sensor unit and a second sensor unit wherein the data processing unit is configured to perform operations comprising: placing the industrial truck in a first orientation with respect to a planar structure, wherein the industrial truck has a length direction, a width direction, and a height direction; detecting the planar structure using the first sensor unit and the second sensor unit and determining, for each of the first sensor unit and the second sensor unit, a distance between the respective sensor unit and the planar structure in the first orientation, wherein the first sensor unit and the second sensor unit each have a respective detection field and supply respective sensor data; placing the industrial truck in a second orientation with respect to the planar structure, wherein at least an angle between the longitudinal axis of the industrial truck and the planar structure differs between the first orientation and the second orientation; detecting the planar structure using the first sensor unit and the second sensor unit and determining, for each of the first sensor unit and the second sensor unit, a respective distance between the respective sensor unit and the planar structure in the second orientation; and deriving, using the sensor data supplied by the first sensor unit and the second sensor unit, the offset of the first sensor unit and the second sensor unit with respect to the length direction and width direction and the angle between the first sensor unit and the second sensor unit with respect to a same spatial axis.

11. The system of claim 10, wherein one of the first sensor unit and the second sensor unit is a laser scanner and the other of the first sensor unit and the second sensor unit is a three-dimensional (3D) area sensor.

12. The system of claim 10, wherein the sensor data supplied by the first sensor unit and the second sensor unit is transformed and mapped in a same coordinate system.

13. The system of claim 10, wherein the data processing unit is further configured to perform, multiple times in at least one further orientation, operations comprising: placing the industrial truck in a second orientation with respect to the planar structure, wherein at least an angle between the longitudinal axis of the industrial truck and the planar structure differs between the first orientation and the second orientation; and detecting the planar structure using the first sensor unit and the second sensor unit and determining, for each of the first sensor unit and the second sensor unit, a respective distance between the respective sensor unit and the planar structure in the second orientation.

14. The system of claim 10, wherein the step of deriving comprises a calculation comprising an averaging, a geometric reconstruction, or the execution of an optimisation function.

15. The system of claim 10, wherein, in one or more of the first orientation, the second orientation, or at least one further orientation, the planar structure lies at least partially within an overlapping area of the detection fields of the first sensor unit and the second sensor unit.

16. The system of claim 10, wherein the planar structure comprises at least two surface portions arranged at an angle to one another.

17. The method of claim 1, further comprising determining a first angle between the first sensor unit and the planar structure and a second angle between the second sensor unit and the planar structure.

18. The method of claim 1, wherein the same spatial axis comprises the height direction.

19. The method of claim 2, wherein the 3D area sensor comprises a time of flight sensor.

20. The method of claim 5, wherein the calculation comprises an averaging, a geometric reconstruction, or an execution of an optimisation function.

Description

[0024] When the present invention is considered together with the accompanying drawings, further advantages and features of the invention will become clearer from the following description of an embodiment. In detail, in the drawings:

[0025] FIGS. 1 and 2 are schematic illustrations of the placement of an industrial truck with respect to a planar structure in a first and a second orientation;

[0026] FIG. 3 is a schematic illustration of the derivation of the offset between the first and the second sensor units of the industrial truck of FIGS. 1 and 2;

[0027] FIG. 4 is a schematic illustration of the placement of an industrial truck with respect to a planar structure which has two surface portions arranged at an angle to one another; and

[0028] FIG. 5 is a schematic illustration of an example in which there is an angular offset between the two sensor units.

[0029] In FIGS. 1 and 2, an industrial truck 10 with a length direction L, a width direction B, and a height direction (not shown) is shown schematically in a plan view, and comprises a laser scanner 12 on the one hand and a time-of-flight camera 14, as a 3D area sensor, on the other hand, as two sensor units. This industrial truck 10 is arranged at a first angle α with respect to a planar structure W in relation to the longitudinal axis L of the industrial truck 10.

[0030] In this state, the two sensor units 12 and 14 detect - in regard to the respective distances and respective angles - the planar structure W. An auxiliary line H1 which runs parallel to the two-dimensional structure W and on which, from the point of view of the laser scanner 12, the time-of-flight camera 14 must be located, can be constructed from the data captured by the two sensor units, beginning with the laser scanner 12. To clarify this concept, several positions of the time-of-flight camera that are plausible for the laser scanner are also shown in FIG. 1, and are each denoted by 14′.

[0031] Furthermore, a second placement of the industrial truck 10 with respect to the planar structure W is shown in FIG. 2, and the corresponding angle between the planar structure W and the longitudinal axis L of the industrial truck 10 is denoted by the angle β. A corresponding detection of the two-dimensional structure W and evaluation of the data from the two sensor units 12 and 14 results in a second auxiliary line H2 that can be constructed and that again indicates plausible positions of the time-of-flight camera 14 for the laser scanner 12 after a determination of the planar structure W has taken place in polar coordinates.

[0032] FIG. 3 indicates how the correct position of the time-of-flight camera 14 in relation to the laser scanner 12 can be determined by constructing an intersection of the two auxiliary lines H1 and H2, so that on the basis of these two captures of the two-dimensional structure W, a corresponding mutual calibration of the two sensor units 12 and 14 to each other with respect to the length direction L, the width direction B, and an angle with respect to the height direction, i.e., a yaw angle, can take place.

[0033] Furthermore, FIG. 4 shows in a similar schematic manner an alternative embodiment of the present invention in which a planar structure W′, with two surface portions W1 and W2 arranged at an angle to one another, is used. The two surface portions W1 and W2 are each at a different angle γ and/or δ to the longitudinal axis L of the industrial truck 10, so that the first and second orientation of the industrial truck relative to the planar structure are available at the same time, and the procedure described with regard to FIG. 1 to FIG. 3 can be carried out in a single pass using the corresponding auxiliary lines H1′ and H2′.

[0034] Finally, FIG. 5 shows a case in which there is a discrepancy between the angles of the two sensor units in the vehicle 10 of FIG. 1. The intended main axis of the laser scanner 12 substantially points in the direction of the longitudinal axis L of the vehicle, whereas the intended main axis of the time-of-flight camera 14 is rotated by a certain angle to the right, as can be seen from the two dashed lines in FIG. 5.

[0035] Accordingly, the two sensor units 12 and 14 also detect the planar structure W at different angles, which are denoted by ε and θ in FIG. 5. If there is an angular discrepancy between the two sensor units 12 and 14 in the manner shown, this can be determined with just a single detection of the planar structure W, by solving for the difference ε - θ, and can be further used to determine the relative mounting position between the two sensor units 12 and 14 and/or can represent a parameter thereof.