DD260052A1 - CONTROL OF THE MOVEMENT PROPERTIES FOR ELASTIC, PLAY-DRIVEN CHASSIS DRIVES OF CRANES - Google Patents

Abstract

The invention relates to a control of Bewegungsvorgaenge for elastic, game geared drives of cranes, especially for those in which arise by the game in the drive or by the Elastizitaet of the structure unwanted vibrational stresses during startup and braking. Such a controller has the task of automatically controlling the movement process in drives of elastic crane designs or in those with game so that unwanted vibration stresses are kept away from the structure and drive. The advantage of the inventive solution is that by reducing the load downtime of the cranes due to destruction of assemblies of the drives or the structure lowered by overuse and that calm times of the landing gear are reduced at the destination. The control is designed in such a way that subordinate torque and speed control loops are used and that the required functions for realizing the motion sequence are provided by a drive computer. Fig. 2

Description

Field of application of the invention

The invention relates to a control of the motion processes for chassis drives of cranes, especially for those in which arise by the game in the drive or by the elasticity of the structure unwanted vibration stresses during startup and braking.

Characteristic of the known technical solutions

Arrangements are known which allow in special cases, a reduction of the stress of crane components with simultaneous positioning.

By arranging a computer for controlling the cat movement in a gantry crane, it is possible to reduce the bending stress in the supports when detecting the bending acceleration of the supports (DE-OS 3005461). The disadvantage is that the effect of the control of the motor current to any play in the drive is disregarded, so that in the starting range overuse of the drive are possible. In addition, the necessary measurement of the bending acceleration is associated with additional technical expenses. Only the trolley and the stroke are considered, not the portal. A method is known in which by specifying a speed setpoint a cosinusoidal acceleration is achieved (C. Poppenhusen: Drives for Conveyor Technology-New Requirements Lead to New Achievements; in Deutsche Hebe- und Fördertechnik, H. 41984, pp. 56-60) , The disadvantage is when the drive in the starting area a game z. B. must go through in the clutch or in the transmission, because this can lead to vibrations of the arranged in the power transmission of rotating masses. The torque output by the engine is thereby also excited to oscillate when the average frequency of upstream controls is greater than the respective natural frequency of the mechanical Schwingungssyslems. The torque stress in the drive can thereby reach a multiple of the kinetostatic torque.

It is also known a method in which the mass is accelerated sinusoidally (R. Schönfeld: control of electric drives with microcomputer controllers, in Electric H. 10 1981, pp. 508-512).

This assumes that the drive system is subject to the maximum of the jerk at time t = 0. The disadvantage is that overstressing can occur when the drive in the starting area has to go through a game.

Object of the invention

It is an object of the invention to provide a motion control system for undercarriage-propelled cranes which reduces the settling time of the system while allowing a reduction in the stress on the engine components as well as on the structure.

Explanation of the essence of the invention

It is the object to develop a control of the motion processes for elastic, game-driven chassis drives of cranes, which allows an automatic approach of a target point, wherein the entire drive system is exposed to a minimum of mechanical stresses. The drive structure should be designed so that lower-level torque and speed control loops are used, which are able to quickly control occurring load sizes such as wind load or fluctuating driving resistance torque.

According to the invention the object is achieved in that a drive computer is a path and time-dependent analog value as a reference variable to the speed or torque control loop. Initially, a torque setpoint dependent on the angular play in the drive is predetermined, which is smaller than the breakaway torque required for the movement of the running gear and just as large as the torque required to move the masses decoupled by the play. After this time, the drive computer gives a travel curve as a reference variable on the speed control loop. The travel curve is designed so that the vibration stress of the drive system during the start-up and braking is a minimum. The course of the curve depends on the respectively highest natural vibration duration of the mechanical vibration system, on the maximum speed and acceleration as well as on the distance to be covered. The drive computer uses several switching points during the driving process, since different equations apply to the setpoint function in accordance with the respective movement state. Shortly before reaching the target position, the drive computer specifies a speed setpoint that corresponds to the crawl speed. When the target position is reached, the speed setpoint becomes zero.

The particular advantage of the solution according to the invention is that a stress-reducing driving is done without the measurement of bending accelerations, shaft rotations or representative sizes is necessary. Prerequisite for determining the desired functions is only the knowledge of the system-immanent time constants. Design changes to the structure or the drive are not required.

embodiment

In the drawing, an embodiment of the invention is shown schematically. It shows:

Fig. 1 Sketch of a movable along a rail gantry crane with a top load Fig. 2 A Signalflußbild the control of a mechanical vibration system consisting of three rotating masses and

Coupling elements Fig. 3 Different temporal courses of motion quantities

As a preferred embodiment, the travel drive of a container gantry crane according to FIG. 1, whose load is retracted during the portal drive. The drive system is moved by a current- and speed-controlled, externally excited DC shunt machine (other embodiments are possible).

2, the output for the speed setpoint voltage U _nS oii (representing speed setpoint) of a drive computer 1 to an input of a speed controller 2 and the output for the current setpoint voltage U; _so n (represents nominal torque value) connected to an input of an armature current control circuit 3, on the basis of the principle of unteriagerten current control and the output of the speed controller 2 is guided. This in turn reaches an input of the drive computer 1. The air gap torque mn formed with the motor field 4 now works on the mechanical vibration system which forms the angular velocity ω _Ί with the integrator 5 of the first _rotating mass (the masses of the rotor of the motor associated mass) the tachogenerator 6 is connected to the second input of the speed controller. By the integrator 7, the angle of rotation cp _{12 is} formed, which operates on the play-related transmission element 8, which communicates with the integrating member 5 of the first rotating mass and the integrating member 9 of the second rotating mass transmission torque mi2. The second rotational speed embodies the rotational masses assigned to the chassis, to which the drag torque m ₂ 2 (eg, driving resistance torque, wind load) additionally acts. The angular velocity ω ₂ communicates with the integrator 6 and with the drive computer 1 via the path integration 10 and the reinforcement 11 and forms the input of the transmission element 12, from which the transmission torque m ₂ 3 is formed, the integrating member 8 of the second rotating mass in Connection stands and works on the integrator 13 of the third rotating mass. The third rotating mass embodies the rotating masses associated with the bridge girder. In addition to the integrating member 13 of the third rotating mass, the resisting torque m ₃₃ (wind load) acts and the output produces the angular velocity ω ₃ , which is connected to the transmission element 9. The blocks 5, 7, 8, 9, 12, 13 represent in their entirety the model of a 3-mass vibration system.

The operation of the controller is the following:

At the beginning of the starting process, the drive computer 1 initially applies the output of the speed controller 2 to electrical ground potential. At the same time, a current setpoint is preset, which generates a constant air gap torque mn, which is equal to the torque mi (FIG. 3). The torque m ^ must be smaller than the breakaway torque required to move the landing gear and just as large as the torque required to move the first rotary mass decoupled by the play. The time constant Ti results

1 f tru - ₍₁₎

The air gap torque In ₁₁ introduced in this way causes the first rotary mass to be accelerated only very slightly for the period of time Ti, from which it follows that also the dynamic transmission torque m ₁₂ after passing through the play-related transmission element 8 is low. A swing of the air gap torque m _t1 in connection with the upstream speed control is suppressed because only the current setpoint is controlled by the drive computer 1 and the speed controller output is at electrical ground potential. After the time T ₁ , the angular play cp _{sp is} overcome and the electrical ground connection of the speed controller output as well as the specification of the current setpoint by the drive computer 1 is canceled. The drive computer 1 now specifies a speed setpoint, which represents the speed setpoint curve 14 (FIG. 2). The time constants result from:

T ₂ = y T _max (n = 1,3,5 ...) _/ (2)

where Tmax is the largest natural vibration duration of the multi-mass vibration system.

V ₄

The choice of the acceleration or jerk profile shown in FIG. 3 makes it possible to influence the maximum speed V ₄ by varying the time constant T ₃ in a very wide range in accordance with the requirements of practical operation without thereby changing the mechanical stresses. The speed setpoint functions to be output by the drive computer 1 result from the speed setpoint and have to be converted according to the "gear ratio." The speed setpoint results briefly

- ^πm \

T ₂

a _m "ι V ₁ = (t sincuRt) for T ₁ <t <(T ₁ + T ₂ ) (6)

2 COd

for (T ₁ + T ₂ X t <(T ₁ + T ₂ + T ₃ )

v ₃ = - ^ L (t + T ₃ -T ₂ - - sin cur (tT ₃ + T ₂ )) (8)

2 cur

for (T ₁ + T ₃ ) <t <(T ₁ + T ₃ + T ₂ )

V ₄ = a _max -T ₃ · (9)

for (T ₁ + T ₃ + T ₂ ) <t <(T ₁ + T ₄ )

V ₅ = - ^ r ² - (t - 2T ₃ - T ₄ sincu _B (tT ₄ )) (10)

2 GJr

for (T ₁ + T ₄ ) <t <(T ₁ + T ₄ + T ₂ ) V ₆ = -a _max (t - ^ - T ₃ - T ₄ ) (11)

for (T ₁ + T ₄ + T ₂ X t <(T ₂ + T ₄ + T ₃ ) V ₇ = __! ^ i. (t -T ₂ -T ₃ -T ₄ sinco _R (t + T ₂ - T ₃ - T ₄ )) (12)

2 COr

for T-, + T ₄ + T ₃ <t <T ₁ + T ₂ + T ₃ + T ₄ - T ₀

The specification of the velocity or speed setpoint according to (12) is aborted when the lowest speed achievable by the drive (creeping speed) is reached (t = T ₁ + T ₂ + T ₃ + T ₄ - T ₀ ), which are up to Retracting to the target position s _z is output as the setpoint. The division of the Schleich process is thus path-dependent, so that the time T ₀ does not have to be determined. Likewise, the beginning of the braking process with

Sbr = S ₀ - ^ p - T ₃ (T ₂ -T ₃ ) (13)

path-dependent.

If the setpoint functions described in (6) to (12) are switched to the speed controller 2 in the form of a speed setpoint, the time behavior of the speed ν to 14, the air gap moment m "to 15, the jerk r to 16, the acceleration a to 17 and the way s to 18 (Fig.3). In the air gap moment mu occur in accordance with the resistance moments m ₂₂ and m ₃₃ fluctuations indicating that disturbances of the input type described are regulated.

Claims (3)

1. Control of the movement processes for elastic, play driving Fahrweksantriebe of cranes, especially for those who are equipped with conventional torque or Stromregeluhgen and speed controls and which results in a game-based multi-mass vibration system due to the elastic construction of the drive and the crane structure, characterized characterized that the output for the speed setpoint voltage U _{n so} n of a drive computer (1) to an input of the speed controller (2) and the output for the current setpoint voltage Ui _so n is connected to an input of an armature current control circuit (3) on the principle of the subordinate Current control and the output of the speed controller (2) is guided, which in turn reaches an input of the drive computer (1) and there can be set to electrical ground potential if necessary, the drive computer (1) via a respective further input the path-time coordinate s _z and the way-Istkoord inate s is supplied. 2. Control according to claim 1, characterized in that the signal waveform is adapted to the drive system in such a way that unwanted settling times and dynamic stresses are avoided or reduced by that according to equation 2, the excitation period (T ₂ ) and the natural oscillation period (T _max ) of the mechanical system are in a fixed relationship to each other. 3. Control according to claim 1 and 2, characterized in that at the beginning of a starting operation of the drive computer (i) for the period (T ₁ ) outputs a torque setpoint or a current setpoint to the torque control loop or current control loop, which causes a constant air gap moment (mi) , Which is smaller than the breakaway torque required for movement of the chassis and just as large as that for moving the decoupled by the game first rotational mass of the mechanical vibration system and that in the further course of the drive computer (1) a speed or. Speed setpoint switches to an input of the speed sensor (2), the waveform of which corresponds to the composite of several Telefunktionen speed setpoint curve (14). For this 3 pages drawings.