Method for controlling an articulated turntable ladder of a rescue vehicle

Abstract

The present invention relates to a method for controlling an articulated turntable ladder (12) of a rescue vehicle (10) wherein the ladder (12) comprises a plurality of telescopically extendable ladder parts (14) by including a tip ladder part (18) pivotable around a horizontal first pivot axis (28) by means of a first pivoting drive. The ladder further comprises a cage (22) connected to the free end of the tip ladder part (18) to be pivoted around a second pivot axis (30) by means of a second pivoting drive. The ladder (12) is pivotably mounted to a base part (16) on top of the vehicle (10) by means of a third pivoting drive to be lifted or lowered around a third pivot axis (32). The method provides for the step of controlling the first pivoting drive such that the absolute inclination angle (α) of the tip ladder part (18) is maintained constant during a lifting or lowering movement of the ladder (12) around the third pivot axis (32).

Claims

1. A method for controlling an articulated turntable ladder of a rescue vehicle, said ladder comprising a plurality of telescopically extendable ladder parts including a tip ladder part that is connected to one or more other ladder parts of the plurality of telescopically extendable ladder parts to be pivoted around a horizontal first pivot axis by means of a first pivoting drive, a cage being connected to a free end of the tip ladder part to be pivoted around a second pivot axis by means of a second pivoting drive, said ladder being pivotably mounted to a base part on top of the vehicle by means of a third pivoting drive to be lifted or lowered around a third pivot axis, said second pivot axis and said third pivot axis being parallel to said first pivot axis, the method comprising: controlling the first pivoting drive such that an absolute inclination angle of the tip ladder part is maintained constant during a lifting or lowering movement of the ladder around the third pivot axis, the absolute inclination angle of the tip ladder part being selected from a set of predetermined absolute inclination angles upon a user input command.

2. The method according to claim 1, further comprising controlling the second pivoting drive such that an absolute orientation of the cage is maintained constant during a lifting or lowering movement of the ladder around the third pivot axis.

3. The method according to claim 1, characterized in that the plurality of different absolute inclination angles comprises at least one of a maximum downward inclination angle of the tip ladder part, a maximum elevation angle of the tip ladder part, and a horizontal angle in which the tip ladder part is held in a horizontal position.

4. The method according to claim 1, characterized in that upon generation of a lifting or lowering command, the ladder is lifted or lowered by operating the third pivoting drive in a first direction, while the first pivoting drive is operated in a second direction opposite to the first direction.

5. The method according to claim 1, characterized in that a position of the tip ladder part is monitored by means of sensors.

6. The method according to claim 1, characterized in that at the end of a lifting or lowering movement of the ladder around the third pivot axis, an absolute position of the tip ladder part and/or the cage is adjusted.

7. A method for controlling an articulated turntable ladder of a rescue vehicle, said ladder comprising a plurality of telescopically extendable ladder parts including a tip ladder part that is connected to one or more other ladder parts of the plurality of telescopically extendable ladder parts to be pivoted around a horizontal first pivot axis by means of a first pivoting drive, a cage being connected to a free end of the tip ladder part to be pivoted around a second pivot axis by means of a second pivoting drive, said ladder being pivotably mounted to a base part on top of the vehicle by means of a third pivoting drive to be lifted or lowered around a third pivot axis, said second pivot axis and said third pivot axis being parallel to said first pivot axis, the method comprising: controlling the first pivoting drive such that an absolute inclination angle of the tip ladder part is maintained constant during a lifting or lowering movement of the ladder around the third pivot axis; and controlling the second pivoting drive such that an absolute orientation of the cage is maintained constant during a lifting or lowering movement of the ladder around the third pivot axis; wherein the absolute inclination angle of the tip ladder part is selected from a set of predetermined absolute inclination angles upon a user input command.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) A preferred example of an embodiment of the present invention will be described in more detail below, with reference to the enclosed drawings, as follows.

(2) FIGS. 1 to 3 are schematic views of a rescue vehicle comprising an articulated turntable ladder according to the present invention in operation, each figure referring to a different operation mode.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

(3) The rescue vehicle 10 in FIG. 1 is equipped with an articulated turntable ladder 12 on top. This articulated turntable ladder (also referred to as “ladder” 12 in the following for the sake of simplicity) comprises a plurality of telescopically extendable ladder parts 14 that are articulated to a base part 16 on top of the vehicle 10, so that the ladder 12 can be lifted or lowered. While all ladder parts 14 are slidably connected to each other so that they can be extended or retracted, a tip ladder part 18 is connected to the remaining ladder parts 20 to be articulated or pivoted around a pivot axis connecting a tip ladder part 18 and the remaining ladder parts 20. At the free end of the tip ladder part 18 (on the left side in FIG. 1), a cage 22 is mounted to be pivoted around another pivot axis. It is further noted that the base part 16 can be turned on top of the vehicle 10 around a vertical turning axis.

(4) This articulated turntable ladder 12 has a large degree of freedom for positioning the cage 22, because of the vertical turning axis of the base part 16, the option of lifting or lowering the ladder parts 14, telescopically extending or retracting the ladder parts 14 from each other, articulating the tip ladder part 18 with respect to the remaining ladder parts 20, while keeping the absolute orientation of the cage 22 so that its bottom 24 is maintained in a constant horizontal position above the ground 26. In all examples described herein, the ground 26 is a flat horizontal plane.

(5) In the following, the pivot axis between the tip ladder part 18 and the remaining ladder parts 20 is designated as first pivot axis 28, a pivot axis connecting the cage 22 to the tip ladder part 18 is designated as second pivot axis 30, and the pivot axis for lifting or lowering the ladder 12 at the base part 18 is designated as third pivot axis 32. The first pivot axis 28 is horizontal, while the second pivot axis 30 and the third pivot axis 32 are also horizontal and parallel to the first pivot axis 28. Each pivot axis 28, 30, 32 is equipped with a corresponding pivoting drive, namely a first pivoting drive for the first pivot axis 28, a second pivoting drive for the second pivot axis 30 and a third pivoting drive for the third pivot axis 32. The pivoting drives are not shown in the figures. By operating one of these pivoting drives, the two elements connected by the respective pivot axis are articulated with respect to each other, i.e. they change their angling position. For example, by operating the third pivoting drive, the ladder 12 is lifted or lowered with respect to the vehicle 10 so that the ladder parts 14 change their angling position with respect to the horizontal ground 26. In the same way, an operation of the first pivoting drive changes the angle between the tip ladder part 18 and the remaining ladder parts 20. The second pivoting drive mainly serves to keep the orientation of the cage 22, as described above, to compensate a change of the absolute inclination angle of the tip ladder part 18. The first pivoting drive, the second pivoting drive and the third pivoting drive are controlled by a control device that generates control commands.

(6) The lower position of the ladder 12 in FIG. 1 designates a position in which the ladder 12 as its lowest possible outreach at an underfloor rescue height, with the remaining ladder parts 20 (with exception of the tip ladder part 18) being positioned horizontally. In this situation the tip ladder part 18 is articulated downwardly, with an inclination angle α with respect to the horizontal plane (i.e. the ground 26) of about 45 degrees. In many rescue situations, a very low outreach of the ladder 12 with a small rescue height is desired. Instead of controlling the pivoting drives for all free pivot axis 28, 30, 32 manually by an operator at the base part 16, as it is known from the state of the art, the articulated turntable ladder 12 according to the present invention provides to keep the absolute inclination angle α of the tip ladder part 18 constant in a determined operation mode during all movements of the ladder 12. For example, if a designated operation mode is selected by the operator, for example, the mode of lowest outreach of the ladder, as shown in FIG. 1, the tip ladder part 18 is automatically driven to keep the absolute inclination angle α as shown, and during all further movements of the ladder, this inclination angle α is maintained. Each inclination angle α corresponds to one selectable mode and is pre-stored in a memory of the control device.

(7) For example, if the third pivoting drive is operated to lift the ladder 12 at the base part 16 and to increase the inclination angle β of the remaining ladder parts 20, the first pivoting drive is operated to decrease the angle γ between the tip ladder part 18 and the remaining ladder parts 20 at the first pivot axis 28 to compensate this increase of the inclination angle β and to keep the absolute inclination angle α of the tip ladder part 18 constant. This is performed automatically by the control device that controls the operation of the first pivoting drive at the pivot axis 28 such that the angle α is constant during a lifting or lowering movement of the ladder 12 around the third pivot axis 32. During this movement, the second pivoting drive is also operated such that the absolute orientation of the cage 22 is maintained constant.

(8) The mode of lowest outreach, demonstrated in FIG. 1, is only one of different possible modes that can be selected by an operator. Once the mode is chosen, the absolute inclination angle α of the tip ladder part 18 is adjusted by the control device, and during the further positioning of the cage 22 in a rescue situation, the operator only needs to control the overall inclination angle of the ladder 12, i.e. the articulation around the third pivot axis 32 at the base part 16 manually, to turn the ladder 12 around its vertical axis, and to extract or retract the ladder part 14 from each other. There is no need to adjust the absolute inclination angle α of the tip ladder part 18 manually. This simplifies the operation of the ladder 12. In practice, upon generation of a lifting or lowering command input by the operator, the ladder 12 is lifted or lowered by operating the third pivoting drive in a respective direction, while the first pivoting drive is operated in the opposite direction to perform the compensation of this movement to keep the absolute inclination angle α.

(9) This compensation by operating the first pivoting drive and the third pivoting drive at the same time can be supplemented by monitoring the position of the tip ladder part 18 by means of sensors that measure the inclination of the tip ladder part 18. If there is a deviation from the desired inclination angle, the sensors give a corresponding correction signal to the control device so that the first pivoting drive can be operated accordingly to perform this correction and to keep the absolute inclination angle α as desired. With other words, there is a feedback about the present inclination angle. In one embodiment, the absolute position of the tip ladder part 18 and/or the cage 22 is adjusted at the end of a lifting or lowering movement of the ladder 12 around the third pivot axis 32.

(10) FIG. 2 shows the articulated turntable ladder 12 that has been described above in connection with FIG. 1 in a different operation mode, corresponding to the different absolute inclination angle α of the tip ladder part 18. In FIG. 2, the tip ladder part 18 is maintained in a horizontal position, i.e. the absolute inclination angle α=0. Two different elevation angles of the ladder 12 with respect to the base part 16 are shown, corresponding to inclination angles β.sub.1 and β.sub.2, with β.sub.2>β.sub.1. To keep α=0 in each of these positions, the angle γ.sub.2 in the position of β.sub.2, i.e. the angle between the remaining ladder parts 20 and the tip ladder part 18, must be smaller than the angle γ.sub.1 in the situation with β.sub.1. As described above, a corresponding mode with an absolute inclination angle α of the tip ladder part 18 can be selected by the operator. The mode in FIG. 2, with the tip ladder part 18 being in a horizontal position, with α=0, corresponds to the maximum outreach of the ladder 12, which can be desired in some rescue situations. It is also noted that with the remaining ladder parts 20 all retracted and the tip ladder part 18 being maintained horizontal, the center of gravity of the rescue vehicle 10 including the ladder 12 is still close to the base part 16, compared with a situation in which at least some of the remaining ladder parts 20 are extracted, shifting the center of gravity side ways from the vehicle 10. This is one reason why choosing the mode shown in FIG. 2 can be desired. Keeping the tip ladder part 18 in its horizontal position is performed in the same way as described in connection with FIG. 1, i.e. by compensating the lifting or lowering movement of the ladder 12 around the third pivot axis 32 by controlling a first pivoting drive 28 by means of the control device, so that no manual adjustment of the absolute inclination angle α of the tip ladder part 18 being necessary.

(11) A third mode that can be selected by the operator is demonstrated in FIG. 3, representing the maximum possible rescue height of the ladder 12. In this position the inclination angle α of the tip ladder part 18 is maximal. Together with moving the tip ladder part 18 into this maximum elevation position, the inclination angle β of the remaining ladder parts 20 can also be moved automatically into its maximum position when the mode of maximum rescue height is selected by the operator. During any further movement of the ladder 12, the maximum inclination angle α of the tip ladder part 18 is maintained constant automatically.