DRIVE SYSTEM FOR MOVING A HEIGHT ADJUSTABLE TABLETOP, TABLE HAVING SUCH A DRIVE SYSTEM, AND METHOD FOR DETECTING COLLISION OF A HEIGHT ADJUSTABLE TABLETOP

Abstract

A drive system (2) for moving a height adjustable tabletop (3) of a table (1) comprises a drive device (4) configured to the move the tabletop (3), a drive control device (5) configured to control the drive device (4), an acceleration sensor (6), and an evaluation unit (7). The acceleration sensor (6) is configured to synchronously follow a motion of the tabletop (3), to detect an acceleration of the sensor motion, and to transmit an acceleration signal corresponding to the sensor motion to the evaluation unit (7). The evaluation unit (7) is configured to evaluate the acceleration signal of the acceleration sensor, to determine a presence of a collision by means of acceleration values exceeding a threshold, and to output a collision signal to the drive control device (5) when the presence of a collision is determined.

Claims

1. A drive system for moving a height adjustable tabletop of a table, comprising: a drive device configured to move the tabletop, a drive control device configured to control the drive device, an acceleration sensor, and an evaluation unit, wherein the acceleration sensor is configured to synchronously follow a motion of the tabletop, to detect an acceleration of the sensor motion, and to transmit an acceleration signal corresponding to the sensor motion to the evaluation unit, and the evaluation unit is configured to evaluate the acceleration signal of the acceleration sensor, to determine presence of a collision by means of acceleration values exceeding a threshold, and to output a collision signal to the drive control device when the presence of a collision is determined.

2. The drive system according to claim 1, wherein the drive device comprises an electric drive motor and a transmission configured to convert a rotational motion of the electric drive motor into a linear motion of the drive device.

3. The drive system according to claim 1, wherein, when a height adjustment of the tabletop happens in an adjustment direction, the acceleration sensor is configured to detect an acceleration in the adjustment direction, and the evaluation unit is configured to evaluate acceleration signals of the acceleration sensor transmitted corresponding to the accelerations in the adjustment direction, and to interpret acceleration values of the acceleration signals in the adjustment direction exceeding a first threshold as presence of a collision.

4. The drive system according to claim 3, wherein the acceleration sensor is configured to detect accelerations in directions not corresponding to the adjustment direction, and the evaluation unit is configured to evaluate acceleration signals of the acceleration sensors transmitted corresponding to the accelerations in the directions not corresponding to the adjustment direction, and to interpret acceleration values of the acceleration signals corresponding to the accelerations in the directions not corresponding to the adjustment direction, which acceleration values exceed a second threshold, as presence of a collision.

5. The drive system according to claim 1, wherein the drive control device is configured to determine and to transmit to the evaluation unit a target speed of the drive device, and the evaluation unit is configured to adjust the first and/or second threshold corresponding to the transmitted target speed in order to enable a collision detection also during an intended speed change.

6. The drive system according to claim 5, wherein the drive system is configured to detect and to transmit to the evaluation unit a detected actual speed of the drive device, and the evaluation unit is configured to adjust the first and/or second threshold corresponding to the transmitted target speed and the transmitted detected actual speed.

7. The drive system according to claim 1, wherein the drive device, the drive control device, the evaluation unit, and the acceleration sensor are provided integrally.

8. The drive system according to claim 7, wherein the drive system comprises a lifting column adjustable in length, and the drive device, the drive control device, the evaluation unit, and the acceleration sensor are provided in the lifting column.

9. A table with a height adjustable tabletop having several drive systems according to claim 1, wherein a communication connecting cable configured to enable a data transmission between the several drive systems is provided between the several drive systems.

10. A method for moving a height adjustable tabletop of a table having a drive system according to claim 1, having the steps: detecting an acceleration of the sensor motion; transmitting the acceleration signal corresponding to the sensor motion to the evaluation unit; evaluating the acceleration signal by the operation unit; determining a presence of a collision by means of acceleration value exceeding a threshold; and outputting a collision signal to the drive control device when determining the collision.

11. The method according to claim 10, wherein the evaluation of the acceleration signal comprises an integration in order to estimate an estimated actual speed.

12. The method according to claim 11, wherein a target speed determined by the drive control device is used for adjusting the threshold.

13. The method according to claim 12, wherein an actual speed detected by the drive system is used for adjusting the threshold.

14. The method according to claim 10, wherein the acceleration signals from the acceleration sensor are processed by a filter.

15. The method according to claim 10 with a table having several drive systems, having the step: transmitting the collision signal from one to the other ones of the several drive systems.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0039] Subsequently, the invention is elucidated by means of embodiments referring to the attached drawings.

[0040] In particular:

[0041] FIG. 1 shows a schematic diagram of a height adjustable table having two drive systems according to the invention; and

[0042] FIG. 2 shows a block diagram of one of the drive systems.

[0043] FIG. 1 shows a schematic diagram of a height adjustable table 1 having two drive systems 2 according to the invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

[0044] The table 1 comprises a height adjustable tabletop 3 connected to the two drive systems 2. In alternative embodiments, the tabletop is not connected to two drive systems 2 but the table comprises merely one single drive system 2 or, in a further alternative, it comprises more than two drive systems 2.

[0045] The drive systems 2 respectively comprise a drive device 4, a drive control device 5, an acceleration sensor 6, and an evaluation unit 7.

[0046] The drive systems 2 further respectively comprise a lifting column 8 adjustable in length. The lifting column 8 adjustable in length consists of three segments which can be moved into another in a telescopic manner. In alternative embodiments, no lifting column 8 adjustable in length but other guiding members are provided, whereby driving forces of the drive device 4 are transmitted to the tabletop 3 in another manner, for example, via chains or steel bands.

[0047] The drive device 4 is configured to move the tabletop 3 in an adjustment direction A. Thereto, in the shown embodiment, the drive device 4 comprises an electric drive motor and a transmission configured to convert a rotational motion of the electric drive motor into a linear motion of the drive device 4. The drive motor comprises control electronics and an incremental position encoder as stroke detection device for detecting a stroke of the drive device 4. In alternative embodiments, the drive device 4 can for example also be designed being a hydraulic cylinder. In alternative embodiments, the control electronics and the incremental position encoder can be replaced by other components for controlling the drive device 4 and being a stroke detection device, for example, a potentiometer.

[0048] The acceleration sensor 6 is configured to synchronously follow a motion of the tabletop 3. This means that the acceleration sensor 6 follows a motion of the tabletop 3 immediately. Thereby, the acceleration sensor 6 detects an acceleration of the sensor motion.

[0049] The drive control devices 5 of the individual drive systems 2 are connected to one another via a communication connecting cable 9 in order to enable data transmission between the drive systems 2.

[0050] The drive device 4, the drive control device 5, the acceleration sensor 6, and the evaluation unit 7 are integrally provided. This means that the drive device 4, the drive control device 5, the acceleration sensor 6 and the evaluation unit 7 are provided as one subassembly. This subassembly is installed in the lifting column 8 and, therefore, it is provided in the lifting column 8. Thereby, the acceleration sensor 6 is arranged on a motor control board of the drive control device 5.

[0051] In alternative embodiments, the drive device 4, the drive control device 5, the acceleration sensor 6, and the evaluation unit 7 are not integrally provided but the individual components are arranged at various suitable places of the table. For example, a central drive control device 5 for several drive systems 2 can be provided in a centrally below the tabletop 3 mounted manner. The respective acceleration sensor 6 of the individual drive systems 2 is then not arranged on the motor control board of the drive control device 5 but in another place on the drive device 4 or in close vicinity of a place of fixation of the drive device 4 to the tabletop 3 in order to synchronously follow the motion of the tabletop 3 in this place of fixation. Moreover, in such a case, no communication connecting cable 9 between the individual drive systems 2 is necessary.

[0052] FIG. 2 shows a block diagram of one of the drive systems 2.

[0053] The drive device 4 having the electric drive motor with control electronics and integral position encoder are connected to the drive control device 5, in this embodiment, designed as being a motor controller. As far as, in an alternative embodiment, the drive device 4 is not provided with an electric drive motor but, for example, with the hydraulic cylinder, the drive control device 5 is designed as being a hydraulic control device.

[0054] The motor controller determines the actual speed and the target speed of the drive motor. This means that the motor controller specifies the target speed of the drive motor and transmits respective control signals to the drive motor, and detects the detected actual speed of the drive motor from increments transmitted from the incremental position encoder of the drive motor to the motor controller. Therefore, the drive control device 5 is configured to control the drive device 4. Thereto, it determines a target speed of the drive device 4 and transmits respective signals to the drive device 4.

[0055] Further, the motor controller executes a synchronization with further columns, therefore, with motor controllers of drive control devices 5 of further drive systems 2 via the communication connection cable 9.

[0056] The acceleration sensor 6 is configured to detect accelerations in the adjustment direction A of the tabletop 3 and in directions not corresponding to the adjustment direction A. In alternative embodiments, the acceleration sensor 6 is either configured to detect only accelerations in the adjustment direction A of the tabletop 3 or only accelerations in the directions not corresponding to the adjustment direction A. In further alternative embodiments, the acceleration sensor 6 is configured to additionally detect a rotation around at least one axis not being parallel to the adjustment direction A.

[0057] The acceleration sensor 6 transmits an acceleration signal corresponding to the sensor motion to the evaluation unit 7. This acceleration signal is transmitted as acceleration (x, y, z) raw data.

[0058] This raw data initially enters a signal processing where the acceleration signal from the acceleration sensor 6 is processed by a filter 10 provided in the drive system 2. This filter 10 is designed as being a digital filter in order to eliminate failures. Depending on a configuration of the acceleration sensor 6 and the evaluation unit 7, in alternative embodiments, the filter 10 can also be designed as being an analog filter or it can be omitted.

[0059] The raw data processed by the signal processing is integrated in an integration and, therefore, failures are furthermore eliminated and a good estimation of the estimated actual speed is achieved.

[0060] The evaluation unit 7 evaluates the acceleration signal from the acceleration sensor 6 by means of a decision logic. Namely, by means of acceleration values exceeding a threshold, the evaluation unit 7 determines that a collision is present. If it is decided that a collision is present, a collision signal, in this case a motor stop signal to the motor controller being the drive control device 5, is output.

[0061] Therefore, when the acceleration sensor 6 merely detecting the acceleration signals in the adjustment direction A is provided, the evaluation unit 7 evaluates the acceleration values of the acceleration signals in the adjustment direction A and, as far as the acceleration values exceed a first threshold, the evaluation unit 7 interprets the acceleration signals as presence of a collision.

[0062] If another kind of acceleration sensor 6 merely detecting acceleration signals in directions not corresponding to the adjustment direction A is provided, the evaluation unit 7 evaluates the acceleration value of the acceleration signals transmitted corresponding to the accelerations in the directions not corresponding to the adjustment direction A and, as far as they exceed a second threshold, the evaluation unit 7 interprets the acceleration signals as presence of a collision.

[0063] The motor controller being the drive control device 5 transmits the determined target speed and the determined actual speed to the decision logic in the evaluation unit 7.

[0064] As the case may be, the evaluation unit 7 adapts the first and second threshold corresponding to the transmitted target speed and the transmitted detected actual speed. Thereby, it is possible to perform a collision determination also during an intended speed change, for example, at a starting and at an ending of the height adjustment motion.

[0065] In use, in a method for moving an adjustable tabletop 3 of a table 1, the acceleration of the sensor motion of the acceleration sensor 6 is detected. Thereby, the acceleration values in all three space directions are detected with a high detection rate. The detection rate is in the range of 100 Hz to 1000 Hz. Alternatively, other, particularly higher, detection rates are also possible insofar as this is admitted by the calculation capacity of a subsequent processing.

[0066] The acceleration signal corresponding to the sensor motion is transmitted to the evaluation unit 7. Thereby, the signal is processed by the digital filter 10 and the subsequent integration such that failures are eliminated in order to achieve an improved estimation of the actual speed. The exact parameters of the signal processing depend on the drive devices and the mechanical design since, depending on that, different kinds of failures can occur. The parameters are adjusted during development or production to a concrete type of drive. Alternatively, the acceleration signals can also be processed by an analog filter 10 or can be directly evaluated.

[0067] The processed speed data are evaluated in the decision logic. Thereby, a collision is determined by means of a quick change of the estimated actual speed, therefore, by an acceleration. In particular, the presence of a collision is determined by means of acceleration values exceeding a threshold.

[0068] The threshold, therefore, as the case may be, the first threshold and/or the second threshold, are adjusted using the target speed determined by the control device 5. Hereby, it is considered that accelerations occur due to the intended speed change included in the determined target speed, for example, at the starting and at the ending of the height adjustment motion, which accelerations must not influence the determination of the presence of a collision in a negative manner.

[0069] Moreover, the threshold, therefore, as the case may be, the first threshold and/or the second threshold are adjusted also using the detected actual speed determined by the drive system 2, wherein the actual speed is determined by the drive control device 5 using the increments detected by the incremental position encoder. Thereby, it is possible to consider the behavior of the drive system 2, particularly delays due to its inertia, during the determination of the presence of a collision.

[0070] Alternatively, the determination of the presence of a collision can also be performed without consideration of the determined target speed and the detected actual speed.

[0071] Insofar as the presence of a collision is determined, a motor stop signal being a collision signal is emitted to the motor controller in order to immediately stop the drive motor. When several drive systems 2 are used, the motor stop signal is particularly transmitted from one of the drive systems 2 to the other drive systems 2.

[0072] All the features represented in the description, the subsequent claims, and the drawing can solitarily or in arbitrary combination be essential for the invention.