DE102007055363A1 - Measurement and control of moving component height on fork lift truck or other working machine, measures vertical acceleration and carries out double integration - Google Patents

Abstract

The truck (1) has a vertical acceleration sensor (6) on the moving component (3) and a reference point (P 3) on the main body (2) of the machine. Vertical acceleration is measured continuously. Double integration of the measured acceleration determines the vertical position of the moving component. The moving component adopts a reference position at least for an instant, during measurement. In this position it occupies a defined location relative to the reference point. The reference position is adopted at least when the machine is started-up. An independent claim IS INCLUDED FOR the corresponding machine.

Description

The The invention relates to a method for measuring and regulating the height a movable component of a work machine. It continues to affect one Work machine with a base component and a movable, height-adjustable Component. Such a work machine, for example, a forklift or a machine with a crane, a height-adjustable Be arm, boom or a lift.

such a Working machines is common to that with the moving component a predetermined height to be approached. Therefore is a measurement of the current height of the moving part over a reference point, typically soils.

To For example, various methods have been proposed the use of a pull-cord potentiometer. This solution requires However, a complicated installation of the rope and is proportionate susceptible to interference.

The DE 101 53 531 A1 describes a radar measurement for detecting the lifting height. Radar measurements are, however, as also proposed laser or ultrasound measurements relatively expensive and also prone to disturbances such as contamination or signal drift. Likewise, the camera monitoring the lifting height is prone to failure, consuming and also hardly automatable.

From the DE 101 53 529 A1 and the US 5,307,698 A is the use of pressure in hydraulic devices or in a liquid-filled measuring tube for altitude measurement known. These solutions require the presence of the hydraulic device or the complex and troublesome installation of a separate hose. They are therefore not suitable for all applications and also not easy to retrofit.

task The invention is therefore a method for measuring the height specify a movable component of a working machine, the particularly reliable and robust and also cost-effective is.

About that In addition, it is another object of the present invention to provide a Working machine with a particularly reliable and technical little expensive device for measuring the height of a indicate moving component of the working machine.

According to the invention this object with the subject of the independent claims solved. Advantageous developments of the invention are Subject of the dependent claims.

An inventive method for measuring the height h _{1 of} an at least vertically movable component of a work machine, wherein the movable member having a first acceleration sensor for measuring a vertical acceleration and a base member of the working machine a reference point for the first acceleration sensor comprises the following steps: Acceleration of the moving component by the first acceleration sensor is measured continuously, whereby a "continuous" measurement here also means measurements with discrete time intervals whose time intervals are small enough to allow sufficiently dense measured values to be provided for the specific application.

Out the measured vertical acceleration is achieved by two-fold integration determines the vertical position of the movable member, wherein the movable component at least at a time of measurement a Reference position occupies, in which the first acceleration sensor has a defined position relative to the reference point. On this way become defined initial or boundary conditions Determination of the integration constants created.

The inventive method has inter alia the Advantage that interfering constructions such as ropes or Hoses can be dispensed with the working machine. In working machines such as forklifts influence unavoidable contamination the measurement is not. In addition, the accelerometers are easy to install and therefore can also be easily retrofitted and being repaired.

In According to one embodiment, the movable component at least at the time of commissioning of the work machine, the reference position. The movable component can also at least in regular Time intervals during operation of the working machine take the reference position. If these intervals can be chosen small enough, can be on an accelerometer dispensed with a particularly high accuracy.

In a preferred embodiment additionally measures a second acceleration sensor, which is arranged stationary to the base member of the working machine, continuously a vertical acceleration of the base member. The second acceleration sensor, for example, arranged in the case of a forklift or on the driver's cab The task is to reproduce vertical movements of the entire machine. Such vertical movements of the entire work machine can be achieved, for example, by moving the work machine to another level via a ramp or a goods lift, and not to enter into the height measurement by the first acceleration sensor.

For a correction of the lifting height is therefore in one embodiment of the method measured by the second acceleration sensor Signal from that measured by the first acceleration sensor Signal subtracted before or after the two-time integration the measured vertical acceleration to determine the vertical Position of the movable member is made. In this way is considered the lifting height only the height of the movable Component detected relative to a reference point of the base member, and not the absolute height of the base member.

In In one embodiment, reaching the reference position detected by the movable member by a contact switch.

In In one embodiment of the invention, the transmission takes place of signals from the first and / or second acceleration sensor an arithmetic unit for calculating the height by a cable. This has the advantage that the transfer is particularly low is prone to failure.

alternative However, the transmission can also be wireless. there is advantageous that no disturbing cable for the transmission must be provided. Instead, you can the transmission takes place by radio, z. B. by means of a wireless radio networking according to the industry standard IEEE 802.15.1 "Bluetooth".

A method according to the invention for regulating the height of a movable component of a work machine comprises the following steps: A desired value h _{soll is set} for the height of the movable component as a reference variable. In addition, an actual value h _is the height of the movable component is determined as a controlled variable according to the method described for the determination of the height. This is followed by a comparison of the actual value of the height with the desired value and an adjustment of the actual value to the desired value by moving the movable component.

A working machine according to the invention with a base component and a movable component comprises a device for determining a height h _{1 of} the movable component. The device for determining the height has a first acceleration sensor for measuring a vertical acceleration of the movable component and a computing unit for calculating the height h _{1 of} the movable component by integrating twice the measured vertical acceleration of the movable component. In this case, the movable component is movable to a reference position in which the first acceleration sensor has a defined position relative to a reference point.

advantageously, the machine has a by the position of the movable member in a reference position operable contact switch. The contact switch is determined by the arrival of the moving component operated in the reference position and the residence of the movable component in the reference position is sent to the arithmetic unit passed. It is also possible to use one or more Contact switch the speed of the moving part when Passage through a reference position.

In In one embodiment, the working machine additionally a second acceleration sensor which is stationary relative to the base component the working machine arranged and for a continuous Measurement of the vertical acceleration of the base component designed is. The second acceleration sensor allows the correction of height measured by the first acceleration sensor on changes in the vertical position of the entire work machine.

In According to one embodiment, the working machine has a transmission device for transmitting signals from the first and / or second Acceleration sensor to a computing unit. In one embodiment is the transmission device for wireless transmission the signals designed.

there However, it is advantageous if the measurement signal of the acceleration sensors already before the transfer by the integration step or the two integration steps are processed. This can be a the corresponding arithmetic unit forming integrator in each case Acceleration sensor arranged or with the acceleration sensor be integrated together in a component. In this case, the transfer already integrated measured values to another processor, the correction of the height of the movable member on the height of the working machine makes itself.

In particular, if a wireless signal transmission is provided, the movable component advantageously has an energy store, for example an accumulator, for the operation of the first acceleration sensor and / or the transmission device. In an advantageous embodiment of the energy storage in the Refe renzposition of the movable component rechargeable.

The Reference position is especially as "charging position" for the energy storage, because at finite intervals, at least during the commissioning of the work machine or during the Operating, is approached. This can be the or a reference position or also be a rest position of the movable component, under Circumstances, it is also particularly advantageous if reference position and rest position agree. For example, it can be provided in a forklift that as a reference position the fork serves its lowered almost at ground level position. This position is also taken by the fork, for example, if the entire forklift is being driven or if it is not is in operation; It is therefore often approached and suitable to charge the energy storage.

The Invention is usable in working machines of various kinds, the a movable and especially height adjustable Have component. The working machine according to the invention can be designed in particular as a forklift. The mobile one However, component can alternatively be designed as a lift be.

embodiments The invention will be described below with reference to the attached Figures explained in more detail.

1 schematically shows a working machine according to an embodiment of the invention and

2 shows a control circuit for controlling the height of a movable component of the working machine according to 1 ,

1 schematically shows a working machine according to the invention, which in the illustrated embodiment, a forklift 1 is. The forklift 1 has a base component 2 up, that on the floor 15 stands. He further has a movable member, which in the embodiment shown a fork 3 is. The fork 3 is height-adjustable on the mast designed as a drawbridge 4 stored and includes a cargo area 5 for a load to be lifted.

At the fork 3 is in a first reference point P _1, a sensor component with a first acceleration sensor 6 provided, together with the fork 3 is height adjustable and with the continuous and / or at certain intervals the vertical acceleration of the fork 3 is measurable. The sensor component further comprises an integrator, not shown, for twice integrating the measurement signal of the first acceleration sensor 6 ,

Near the ground of the mast 4 in a second reference point P _2, a second acceleration sensor 7 provided, firmly on the mast 4 mounted and thus not height adjustable. The second acceleration sensor 7 serves as a reference value transmitter for the first acceleration sensor 6 , If the second acceleration sensor 7 measuring a non-zero vertical acceleration, this is necessarily due to the fact that the entire work machine 1 undergoes a vertical acceleration, for example when driving over a ramp. However, such vertical acceleration of the entire machine should not be included in the Hubhöhenmessung. The undesired contribution can be calculated out of the optionally twice integrated measurement signal of the first acceleration sensor with the aid of the measuring signal of the second acceleration sensor, which may already be integrated twice.

At the mast 4 is a contact switch in a third reference point P ₃ 16 intended. He is in a known height h ₃ and is through the fork 3 triggered at the moment in which h ₁ = h ₃ , the fork 3 So exactly at the height of the contact switch 16 located. Thus, the fork takes 3 at certain times in each case the precisely defined reference height h ₃ , which allows the determination of the required integration constants.

In the embodiment shown, the work machine is a forklift 1 for example, to lift loads to a certain height or to lower them from a certain height. This can be a driver of the forklift 1 According to the invention specify a desired height h ₁ , which is to be approached. The desired height h ₁ will then, as related to 2 described as the setpoint of a regulation of the amount used.

Wants the driver of the forklift 1 no fixed height h ₁ for the fork 3 pretend he can fork 3 also operate manually and can be calculated from the acceleration measurements calculated height h _1, for example, on a display.

2 shows an example of a control loop 8th for regulating the height of a movable component of the working machine, for example the height of the fork 3 of the forklift 1 according to 1 , By the driver or the operator of the working machine or by an automatic operation of the setpoint h _{is set} for the height h ₁ and serves as a reference variable in the control loop 8th ,

A position controller 13 is applied with the difference from the setpoint h _soll and the specific actual value h _ist . Its output is on a device for height variation 10 the fork 3 given for example, in a hydraulically actuated fork 3 may be a proportional valve of a lifting cylinder. In addition to the automatic control of the fork height is also a manual operation 14 provided, the alternative or supplementary z. B. can be used for post-correction.

The device for height variation 10 represents a fork height 9 one. To determine the fork height 9 become acceleration measurements 11 whose result is at least the measured value a (t ₁ ). From these measured values, a double integration with the arithmetic unit is achieved 12 the actual value h _is the fork height determined, wherein by approaching the reference height h ₃ through the fork 3 the integration constants are determined. The actual value of h _is of the fork height is _intended to form the difference from the target value h and the determined actual value have used as an input to the position controller.

The arithmetic unit 12 can be acted upon with further measured values (not shown) to a correction of the determined actual value h _is to perform on sizes such as a vertical acceleration of the entire forklift and thus to improve the quality of the height determination.

1

fork-lift truck

2

basic component

3

fork

4

mast

5

load area

6

first accelerometer

7

second accelerometer

8th

loop

9

fork height

10

Facility to the height variation

11

acceleration measurements

12

computer unit

13

position controller

14

manual service

15

ground

16

contact switch

h ₁

height of the first reference point

h ₂

height of the second reference point

h ₃

height of the third reference point

P ₁

first reference point

P ₂

second reference point

P ₃

third reference point

h _should

setpoint for the fork height

h _is

actual value the fork height

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10153531 A1 [0004]
• - DE 10153529 A1 [0005]
• - US 5307698 A [0005]

Claims (18)

Method for measuring the height h _{1 of} an at least vertically movable component ( 3 ) of a work machine ( 1 ), wherein the movable component ( 3 ) a first acceleration sensor ( 6 ) for measuring a vertical acceleration and a base component ( 2 ) of the working machine ( 1 ) a reference point (P ₃ ) for the first acceleration sensor ( 6 ), the method comprising the steps of: - continuously measuring the vertical acceleration of the moving component ( 3 ) by the first acceleration sensor ( 6 ); Twice the integration of the measured vertical acceleration to determine the vertical position of the movable component ( 3 ), wherein the movable component ( 3 ) assumes a reference position at least at a time of the measurement in which the first acceleration sensor ( 6 ) has a defined position relative to the reference point (P ₃ ). Method according to claim 1, wherein the movable component ( 3 ) at least at the time of commissioning of the working machine ( 1 ) assumes the reference position. Method according to claim 1 or 2, wherein the movable component ( 3 ) at least at regular intervals during operation of the work machine ( 1 ) assumes the reference position. Method according to one of claims 1 to 3, wherein additionally a second acceleration sensor ( 7 ), which is fixed to the base component ( 2 ) of the working machine ( 1 ) is arranged, continuously a vertical acceleration of the base member ( 2 ) measures. Method according to claim 4, wherein the second acceleration sensor ( 7 ) measured signal from that by the first acceleration sensor ( 6 ) is subtracted before the two-time integration of the measured vertical acceleration to determine the vertical position of the movable component ( 3 ) is made. Method according to one of claims 1 to 5, wherein the achievement of the reference position by the movable component ( 3 ) by a contact switch ( 16 ) is detected. Method according to one of claims 1 to 6, wherein the transmission of signals from the first and / or second acceleration sensor ( 6 . 7 ) to a computing unit ( 12 ) through a cable. Method according to one of claims 1 to 7, wherein the transmission of signals from the first and / or second acceleration sensor ( 6 . 7 ) to a computing unit ( 12 ) takes place wirelessly. Method for regulating the height h _{1 of} a movable component ( 3 ) of a work machine ( 1 ), the method comprising the following steps: predetermining a setpoint value h _soll for the height of the movable component ( 3 ) as a reference variable; Determination of an actual value h _is for the height of the movable component ( 3 ) as a control variable according to the method according to one of claims 1 to 8; - Comparison of the actual value h _is the height with the setpoint h _soll and equalization of the actual value h _is to the setpoint h _soll by moving the movable component ( 3 ). Working machine ( 1 ) with a base component ( 2 ) and a movable component ( 3 ), whereby the working machine ( 1 ) means for determining the height h _{1 of} the movable member ( 3 ) comprising: - a first acceleration sensor ( 6 ) for measuring a vertical acceleration of the moving component ( 3 ), - a computing unit ( 12 ) for calculating the height h _{1 of} the moving component ( 3 ) by twice integrating the measured vertical acceleration of the moving component ( 3 ), wherein the movable component ( 3 ) is movable to a reference position in which the first acceleration sensor ( 6 ) has a defined position relative to a reference point (P ₃ ). Work machine according to claim 10, wherein the working machine ( 1 ) one by the position of the movable component ( 3 ) in a reference position operable contact switch ( 16 ) having. Work machine according to claim 10 or 11, additionally comprising a second acceleration sensor ( 7 ) which is stationary relative to the base component ( 2 ) of the working machine ( 1 ) and for a continuous measurement of the vertical acceleration of the base component ( 2 ) is designed. Work machine according to one of claims 10 to 12, which comprises a transmission device for transmitting signals from the first and / or second acceleration sensor to the computing unit (11). 12 ) having. Work machine according to claim 13, wherein the transmission device designed for wireless transmission of signals is. Work machine according to claim 13 or 14, wherein the movable member is an energy store for the operation of the first acceleration sensor ( 6 ) and / or the transmission device. Work machine according to claim 16, wherein the energy store in the reference position of the movable member is rechargeable. Work machine according to one of Claims 10 to 16, which are used as forklifts ( 1 ) is trained. Work machine according to one of claims 10 to 16, wherein the movable member designed as a lift is.