JP2000143183A - Elevating system control method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute the control with high accuracy by synchronously lifting and lowering the elevators by respectively determining the moving amounts of elevators in each control period. SOLUTION: In this elevating system control method, a position and a speed of each elevator 11, 12, 13, 14 are determined on the basis of the result of the detection by each detector D1, D2, D3, D4 in each control period, a position where each elevator 11, 12, 13, 14 is to be moved until a start time of the next control period is determined on the basis of the determined position and speed, then a moving amount to the start point of the next control period, of each elevator 11, 12, 13, 14 is determined on the basis of the determined position and speed, and each driver DR1, DR2, DR3, DR4 is controlled for driving each motor M1, M2, M3, M4 corresponding to the determined moving amount of each elevator 11, 12, 13, 14 to lift and lower the elevators 11, 12, 13, 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for synchronously controlling each lifting device of a lifting system in which a plurality of lifting devices are combined, and a control device therefor.

[0002]

2. Description of the Related Art In an elevating system in which a plurality of elevating devices such as jacks, electric cylinders, and hydraulic cylinders are combined and controlled synchronously to elevate an object, if the elevating amount of each elevating device is not synchronized, the object to be elevated is lowered. Is tilted and a dangerous state occurs, so that it is necessary to strictly synchronize the lifting amounts of the lifting devices.

FIG. 1 is a schematic diagram showing a configuration example of such a conventional system in which four lifting devices are combined. In this conventional example, the four lifting devices S are connected by a fastening shaft R and a gear box G, and are driven by a motor M as one actuator to be moved up and down, thereby achieving mechanical synchronization. ing. However, in such a mechanically synchronized configuration, it may not be possible to fasten the lifting devices S with the fastening shaft R and the gearbox G depending on the surrounding circumstances.

It is also possible to use a hydraulic cylinder as an elevator and a hydraulic pump as an actuator. In that case, it is necessary to connect the hydraulic pump and each hydraulic cylinder with a hydraulic hose, but depending on the surrounding conditions, there may be cases where the hydraulic pump and each hydraulic cylinder cannot be connected with a hydraulic hose, as described above. obtain.

In order to solve the above-mentioned problem, for example, as shown in a schematic diagram of FIG.
The electric motors M1 to M4 are attached to the respective S1 to S4, and the respective motors M1 to M4 are synchronously driven, and the brakes attached to the respective electric motors M1 to M4 are synchronously controlled, so that the elevating amounts of the respective elevating devices S1 to S4 respectively A configuration for synchronizing is also in practical use. However, each of the motors M1 to M4 shown in FIG. 2 needs to be, for example, an induction motor capable of performing synchronous control.

[0006] In this case, it is also possible to use a hydraulic cylinder as an elevator and a hydraulic pump as an actuator. In that case, it is necessary to attach a hydraulic pump to each hydraulic cylinder and drive each hydraulic pump synchronously.

[0007]

However, in the above-described configuration in which the electric motors are attached to the respective lifting and lowering devices and the synchronous driving is performed, there is a problem that the accuracy of the synchronous control is actually poor. More specifically, since the voltage applied to each motor is either 0 V or the rated voltage, on / off control is performed, and accurate synchronization cannot be obtained with a motor having poor response. There was a problem. In response to such a problem, for example, attempts have been made to adjust the speed using a brake attached to each electric motor. However, such a brake is generally an electromagnetic brake and originally intended for stopping. Therefore, the responsiveness is not so good, and it is not suitable for use in speed control. Therefore, there is also a problem that it is necessary to separately attach, for example, a powder brake or the like having good responsiveness, in addition to the stopping brake originally attached to each electric motor. Such a problem similarly occurs when a hydraulic cylinder is used as a lift and a hydraulic pump is used as an actuator, for example.

Further, conventionally, in order to determine the stop position of the lifting / lowering device, the coasting amount after the voltage applied to the motor is set to 0 V is measured in advance, and the actual stop position is determined based on the result of the measurement. Was controlled so that the voltage applied to the motor was 0 V. However, such coasting amount is
Since it varies according to the load of the lifting device, that is, the weight of the object lifted by the lifting device, there is another problem that the stopping accuracy cannot be maintained. In order to solve such a problem, the coasting amount of the electric motor may be measured in advance in accordance with the weight of the object lifted and lowered by the lifting device, but this becomes very complicated in practical use.

The present invention has been made in view of such circumstances, and a control of a lifting system capable of accurately and synchronously operating the lifting and lowering of each lifting device of a lifting system combining a plurality of lifting devices. It is intended to provide a method and a control device.

[0010]

According to a first aspect of the present invention, there is provided a plurality of elevating devices having an elevator, an actuator for elevating the elevator, a driver for driving the actuator, and a detector for detecting a position of the elevator. In a control method of a lifting system that moves to a designated destination position by synchronously ascending and descending by controlling each of the drivers based on the detection result of the detector for each control cycle,
A first step of obtaining the position and speed of each elevator according to the detection result of each detector, and each elevator reaching the start time of the next control cycle based on the position and speed obtained in the first step. A second step of obtaining a target position to be obtained, and a third step of obtaining a movement amount to be moved by the start time of the next control cycle of each elevator based on the target position obtained in the second step; The fourth step of controlling each driver to drive each actuator in accordance with the movement amount of each elevator obtained in the third step is repeated in each control cycle.

In the control method of the lift system according to the first aspect of the present invention, the amount of movement of each lift is determined in each control cycle, and each lift moves up and down in synchronization with each other. Done.

According to a second aspect of the present invention, in the first aspect, the second step is a step of determining a position of the elevator from the designated destination position based on the position of each elevator obtained in the first step. A fifth step of identifying a lift located at a distant position, and the following steps for each lift based on the position and speed obtained in the first step with reference to the position of the lift identified in the fifth step. And a sixth step of obtaining a target position to be reached by the start of the control cycle.

In the second aspect, since the control is performed based on the elevator having poor followability among the plurality of elevators, high-precision control is performed even if the performances of the plurality of elevators do not match.

According to a third aspect of the present invention, a plurality of elevating devices having an elevator, an actuator for elevating and lowering the elevator, a driver for driving the actuator, and a detector for detecting the position of the elevator are provided for each control cycle. Controlling the drivers based on the detection results of the detectors so as to move up and down synchronously to move to a designated destination position. First means for obtaining the position and speed of each elevator according to the result; and in each control cycle, each elevator reaches the start time of the next control cycle based on the position and speed obtained by the first means. A second means for determining a target position to be moved, and in each control cycle, each elevator should be moved to a start time of a next control cycle based on the target position obtained by the second means. A third means for obtaining a moving amount; and a fourth means for controlling each driver to drive each actuator in accordance with the moving amount of each elevator obtained by the third means in each control cycle. It is characterized by having.

[0015] In a fourth aspect based on the third aspect, the second means is configured to determine the most specific position from the designated destination position based on the position of each elevator determined by the first means. Fifth means for specifying a lift located at a distant position, and, based on the position and speed obtained by the first means, with reference to the position of the lift specified by the fifth means, Sixth means for obtaining a target position to be reached by the start of the control cycle.

According to the third and fourth aspects of the present invention, a control device capable of executing the method of the first and second aspects of the present invention by a computer is realized by programming each means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 3 is a block diagram showing a configuration example of a lifting system controlled by the first embodiment of the control device of the lifting system of the present invention. However, in this example, a case in which four elevating devices are controlled is shown. However, if two or more elevating devices are controlled, basically the same configuration can be adopted regardless of the number of elevating devices.

The four lifting / lowering devices S1, S2, S3, S4 are respectively electric motors M1, M2, M3, M4 and electric motors M1, M2, M3, M4.
Lifting devices (hereinafter referred to as lifting devices) 11, 12, 13, and 14, which are driven up and down by the motors, brakes B1, B2, B3, and B4 for controlling braking of the motors M1, M2, M3, and M4, and motors M1, M
2, by detecting the rotation speed of M3, M4
Detectors D1, D2, D3, D4 that detect the elevation of 2, 13, 14
And each motor M1, M2, M
3, drivers DR1, DR2, DR3, DR4 for driving and controlling M4. The brakes B1, B2, B3, B4 are controlled by the control device 1, and the detectors D1, D2, D3, D4
Is input to the control device 1 via the drivers DR1, DR2, DR3, DR4.

In the first embodiment, each motor M1, M2, M3, M4 is a servomotor, each driver DR1, DR2, DR3, DR4 is a servo driver, and each detector D1, D2 , D3 and D4 use encoders respectively.

FIGS. 4 and 5 are flowcharts showing a control procedure for synchronously controlling the lifting devices S1, S2, S3, and S4 by the control device 1. The main routine shown in FIG. And an interrupt routine shown in FIG. Hereinafter, the control method of the lifting device according to the present invention will be described with reference to these flowcharts.

First, when the operation of the lifting system is started, initial values of control parameters are input to the control device 1 in advance (step S10). The parameters to be input to the control device 1 include the lift amount of each of the motors M1, M2, M3, and M4 per one rotation of the lifts 11, 12, 13, and 14, and the lifts 11, 1
Driving acceleration time and deceleration time of 2, 13, 14 and each detector D1, D
2, D3, D4 resolution, rated motor speed of each motor M1, M2, M3, M4.

Next, the control device 1 uses the parameters input in step S10 to make each of the elevators 11, 12, 13, 14
Generate an acceleration pattern and a deceleration pattern for driving the vehicle and store them as an acceleration / deceleration curve table (step S1
2). Next, the control device 1 controls the drivers DR1, DR2, DR3, DR4
Control (interrupt routine) for giving a command value to the CPU (step S14). As a result, the interrupt control is executed in each control cycle after this point. Further, the control device 1 releases the brakes B1, B2, B3, B4, which have fixed the electric motors M1, M2, M3, M4 until then (step S16).
When the brakes B1, B2, B3, and B4 are released, the elevators 11, 12, 13, and 14 enter a non-braking state until an interrupt control ON command is output in step S22 described below. However, the drivers DR1, DR2, DR3, and DR4 are fixed at the current position by performing servo lock control as described later.

After the interruption control is permitted, each detector D1, D
If D2, D3, D4 are of the incremental type, an origin return operation for setting a reference position is performed (step S18). However, if the detectors D1, D2, D3, D4 are of the absolute position type, this home return operation is not necessary.

The preparation for operating the lifting system, specifically, the preparation for moving the elevators 11, 12, 13, and 14 up and down is now completed.
14 instructs each of the drivers DR1, DR2, DR3, DR4 of the destination position and the operating speed which are the ultimate positions to be reached.
(Step S20) Then, an instruction to turn on the interrupt control is issued (Step S22). When this interrupt control ON is commanded, the elevators 11, 12, 13, and 14 are actually lifted and lowered by the interrupt routine, and as a result, each elevator at the speed specified by the controller 1 in step S20. 11, 12, 13, and 14 start going up and down. Eventually, when each of the elevators 11, 12, 13, and 14 moves to the destination position instructed by the control device 1 in step S20 ("YES" in step S24), each of the motors M1, M2, M3, and M4 is in a servo locked state. And is fixed at the destination position.

Thereafter, if it is necessary to raise and lower each of the elevators 11, 12, 13, and 14 again ("YES" in step S26), the control device 1 returns the processing to step S20 and returns to the next destination. The instructions of the position and the operating speed are given to each driver DR1, DR2, DR3,
By giving the signal to DR4, the operation can be performed in the same manner as described above. Finally, when ending driving (Step
"NO" in S26), and the control device 1 controls the drivers DR1, DR2, DR3,
An instruction to stop the operation is given to DR4, and each of the elevators 11, 12, 13, and 14 is fixed at the current position by controlling each of the brakes B1, B2, B3, and B4 to the braking state (step
S28).

Next, the interrupt routine shown in FIG. 5 will be described. This interrupt routine is individually executed for each of the lifting / lowering devices S1, S2, S3, S4 in each control cycle after the interrupt control is permitted in step S14 of the main routine. However, until the interrupt control ON is commanded in step S22 of the main routine,
Different procedures are performed thereafter.

From the time point when the interrupt control is permitted in step S14 of the main routine to the time when the interrupt control ON is instructed in step S22 ("N" in step S32)
O "), the elevators 11, 12, 13, and 14 are not operated, and so-called servo lock control is performed. First, the control device 1 controls the detectors D1, D2, D3, and D4 to detect Read the current position of motors M1, M2, M3, M4 (step S3
8), the travel position required for each of the elevators 11, 12, 13, and 14 is calculated by comparing the target position, which is the position to be reached in the next control cycle, with the current position. Since it is a position, the movement amount is “0”. Therefore, each elevator 1
The interrupt routine is ended without performing the movement of steps 1, 12, 13, and 14 (steps S40 and S42).

However, even when the operation is stopped, step S4
The movement amount calculated by 0 is not always “0”. The reason is that when the brakes B1, B2, B3, B4 of the motors M1, M2, M3, M4 are released, each elevator
This is because 11, 12, 13, and 14 may move from the original stop position for some reason. However, the moving amount in this case is very small, and the control device 1 controls the drivers DR1, DR2, DR3, DR4 of the elevators 11, 12, 13, and 14 whose moving amount is not “0”.
To the motors M1, M2, M
3, each elevator by driving M4 11, 12, 13, 14
Is moved to the target position (in this case, the original current position) (steps S40 and S42). The control for constantly maintaining the control target in the current state in this manner is the servo lock.

On the other hand, after the interrupt control ON is instructed in step S22 of the main routine ("YE" in step S32).
S "), control is performed to actually raise and lower each of the elevators 11, 12, 13, and 14. First, the operation state at that time, specifically, whether the vehicle is in the acceleration state, the constant speed state, or the deceleration state It is determined whether the vehicle is in the stop state or in the stop state (step S34) .As a result, in any state other than the stop state, the target position which is the position to be reached in the next control cycle is determined. The target speed required to move to is determined by referring to the acceleration / deceleration curve table generated in step S12 of the main routine (step S36), provided that it is determined in step S34 that the vehicle is in the constant speed state. Is the operating speed previously determined in step S20 of the main routine as the target speed.

When the target position to be reached in the next control cycle is determined in this way, the control device 1
Are the motors M1, M detected by the detectors D1, D2, D3, D4
2.Read the current positions of M3 and M4 (step S38), calculate the difference between the current position and the target position as the travel distance, and instruct each driver DR1, DR2, DR3, DR4 to travel by that travel distance. Output (Step S40), and each detector D1, D2, D3, D4
When it is detected that the vehicle has reached the target position based on the detection value of (i), the movement of each of the elevators 11, 12, 13, and 14 ends (step S42).

As described above, step S1 of the main routine is performed.
After the execution of the interrupt routine is permitted in step 4, the above-described interrupt routine is executed in each of the predetermined control cycles, so that the servo control is performed until the control device 1 issues an interrupt control ON command. Lock control is performed, and each elevator 11, 12, 13, 14 is fixed at the current position, and after the interrupt control ON is commanded, each elevator 11, 11,
When 12, 13, and 14 move to the target positions, they eventually move to the destination positions instructed by the control device 1 and stop.

Next, a second embodiment of the present invention will be described. FIGS. 6 and 7 show an induction motor instead of a servo motor as the motors M1, M2, M3, and M4, and drivers DR1 and DR4.
It is a flowchart which shows the control procedure of the control apparatus 1 of 2nd Embodiment of this invention at the time of using an inverter instead of a servo driver as 2, DR3 and DR4, respectively.

The motors M1, M2, M3,
The induction motor used as M4 has a lower low-speed torque than the servomotor used in the first embodiment, and cannot perform self-fixing control such as servo lock. Be sure to apply the brakes at the time of completion of movement, etc.
2. It is necessary to make the input to the inverter used as DR3, DR4 "0" to stop at the destination position. Therefore, even in the interrupt routine, while the interrupt control ON is not instructed in the main routine, each motor is controlled.
It is necessary not to perform control that drives M1, M2, M3, and M4.

More specifically, in the main routine of the first embodiment, steps S14 and S18 are performed.
The brake is released in step S16 after the interruption control between the steps S1 and S2 is permitted. However, in the second embodiment, the control for releasing the brake is not performed.
In 2, the brake is released together with the output of the interrupt control ON command. In other words, step S14
Even if the interrupt control is permitted and the interrupt routine is executed in step S22, the motors M1, M2, M3, and M4 are in a brake-applied state until the brakes B1, B2, B3, and B4 are released in step S22. Is maintained.

In the first embodiment, the brake is applied in step S28 at the end of the operation. However, in the second embodiment, the movement to one destination position is completed. In other words, each time one operation is completed, in step S25, each motor
Stop M1, M2, M3, M4 and brake B1, B2, B
3, Activate B4 and disable interrupt control by instructing interrupt control off.

Further, in the first embodiment, when the interrupt control ON is not instructed, the control jumps from step S32 to step S38 of the interrupt routine to perform the servo lock control. In the interrupt routine according to the second embodiment, as shown in FIG. 7, when the interrupt control ON is not instructed, the interrupt routine is directly terminated from step S32.

The control procedures of the first embodiment other than those described above are the same as those of the above-described first embodiment.
Thus, in the second embodiment, the motor M
1, M2, M3, M4 as induction motors and drivers DR1, DR2,
Since inverters are used as DR3 and DR4, self-fixing control such as servo lock cannot be used, so that each of the elevators 11, 12, 13, and 14, in other words, each motor M
1, M2, M3, M4
Control is performed to stop M2, M3, and M4, and the current position is maintained by operating the brakes B1, B2, B3, and B4 to apply the brakes.

FIG. 8 is a block diagram showing a configuration example of a third embodiment of the lifting system according to the present invention. In the third embodiment, the detectors D1, D2, D3, and D4 are replaced by the electric motors M1, M2, M3, and M4 in the first and second embodiments.
Instead of detecting the rotation speed of each elevator,
It is configured to directly detect 14 positions (elevation amount).

With such a third configuration, control with higher precision is possible as compared with the first and second embodiments.
Depending on the environment in which the lifting system is installed, the detectors D1, D2, D3, and D4 directly detect the rotation speeds of the motors M1, M2, M3, and M4 as in the first and second embodiments. In some cases, a configuration must be adopted.

The control procedure by the control device 1 according to the third embodiment is similar to that of the first embodiment.
Servo motors for M2, M3, M4 and drivers DR1, DR2, DR3,
When using a servo driver for DR4, the first
Similar to the second embodiment, the flowcharts shown in FIGS. 4 and 5 include the motors M1, M2,
Induction motors on M3, M4 and drivers DR1, DR2, DR3, DR4
In the case where the inverters are used, the flowcharts shown in FIGS. 6 and 7 become the same as in the second embodiment.

In the second embodiment, the induction motors are used as the motors M1, M2, M3, and M4, and the inverters are used as the drivers DR1, DR2, DR3, and DR4. There is a possibility that the actual positions of the elevators 11, 12, 13, and 14 may be inconsistent due to the shift in the response in the above. When such a phenomenon occurs, an object to be lifted and lowered by the lifting and lowering system is tilted, thereby causing a very dangerous state. Therefore, even if the actual position of each of the elevators 11, 12, 13, and 14 constituting the elevator system of the present invention is shifted, the actual positions of all the elevators 11, 12, 13, and 14 are changed as quickly as possible. It is desirable to match the positions.

The fourth embodiment of the lifting system according to the present invention has been made from such a viewpoint. The configuration of the fourth embodiment is similar to the configuration of the third embodiment, and only the interrupt routine in the control procedure by the control device 1 is different.

In the fourth embodiment, step S40 of the interrupt routine of the third embodiment shown in FIG.
Between step S42 and step S42, as shown in FIG. 9, a step S4 for obtaining the elevator farthest from the destination position (movement is the slowest) among the elevators 11, 12, 13, and 14 as shown in FIG.
1A processing and the elevator 11 (or 1
(2, 13, 14), the position deviation of the other elevator is calculated, the value of each k times is subtracted from the movement amount of each elevator calculated in step S40, and the result is calculated in the next control cycle. The process of step S41B as a movement amount is performed.

By executing the processing of steps S41A and S41B of the interrupt routine of the fourth embodiment in each control cycle, the actual position of each of the elevators 11, 12, 13, and 14 is controlled by each control cycle. It is controlled to be as uniform as possible in the cycle.

In each of the above embodiments, an example in which a motor is used as an actuator has been described. However, a configuration in which, for example, a hydraulic cylinder is used as an elevator and a hydraulic pump is used as an actuator is also possible. In such a case, the driver controls the power source of the hydraulic pump, more specifically, the electric motor that drives the hydraulic pump, and the detector detects the discharge amount of the hydraulic pump or directly detects the displacement of the hydraulic cylinder. May be configured.

[0046]

As described above in detail, according to the control method of the lift system of the first invention, the amount of movement to be moved by each lift in each control cycle is obtained, and each lift is moved synchronously. Therefore, highly accurate control is performed.

According to the second aspect of the present invention, since the control is performed based on the elevator having poor followability among the plurality of elevators,
Even if the performances of a plurality of elevators do not match, high-precision control is performed.

Further, according to the third and fourth aspects of the present invention, a computer which can execute the method of the first and second aspects of the present invention is realized by programming each means.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration example of a conventional lifting system in which four lifting devices are combined.

FIG. 2 is a schematic diagram showing another configuration example of a conventional lifting system combining four lifting devices.

FIG. 3 is a block diagram illustrating a configuration example of a lifting system controlled by a first embodiment of a control device of the lifting system according to the present invention.

FIG. 4 is a flowchart showing a control procedure of the first embodiment of the control device of the lifting system according to the present invention.

FIG. 5 is a flowchart showing a control procedure of the control device of the lifting system according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing a control procedure of a control device for a lifting system according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing a control procedure of a control device for a lifting system according to a second embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration example of a lifting system controlled by a third embodiment of the control device of the lifting system of the present invention.

FIG. 9 is a flowchart showing a control procedure of a fourth embodiment of the control device of the lifting system according to the present invention.

[Description of Signs] 1 Controller 11, 12, 13, 14 Elevator S1, S2, S3, S4 Elevator M1, M2, M3, M4 Motor D1, D2, D3, D4 Detector DR1, DR2, DR3, DR4 Driver

Claims (4)

[Claims] An elevator, an actuator for lifting and lowering the elevator, a driver for driving the actuator,
A plurality of elevators having a detector for detecting the position of the elevator, and a designated movement by synchronously ascending and descending by controlling each of the drivers based on a detection result of the detector for each control cycle. In a control method of a lift system for moving to a previous position, a first step of obtaining a position and a speed of each lift according to a detection result of each detector; A second step of obtaining a target position to be reached by the start of the next control cycle, and moving to a start point of the next control cycle of each elevator based on the target position obtained in the second step. A third step of obtaining a moving amount to be performed; and a fourth step of controlling each driver to drive each actuator in accordance with the moving amount of each elevator obtained in the third step. Is repeated for each control cycle. 2. The method according to claim 1, wherein the second step comprises: a fifth step of specifying a lift furthest from the designated destination position based on the position of each lift obtained in the first step. Based on the position and speed obtained in the first step, with reference to the position of the elevator specified in the fifth step, a target position to be reached by the start time of the next control cycle of each elevator is determined. The method according to claim 1, further comprising a sixth step of determining. 3. An elevator, an actuator for lifting and lowering the elevator, a driver for driving the actuator,
A plurality of elevators having a detector for detecting the position of the elevator, and a designated movement by synchronously ascending and descending by controlling each of the drivers based on a detection result of the detector for each control cycle. In the control device of the lift system to be moved to the previous position, in each control cycle, first means for obtaining the position and speed of each elevator according to the detection result of each detector; and in each control cycle, the first means for obtaining the position and speed. Means for obtaining a target position that each elevator should reach by the start of the next control cycle, based on the position and speed, and for each control cycle, based on the target position obtained by the second means. A third means for calculating a movement amount of each elevator to be moved by the start of the next control cycle; and a control means for each control cycle corresponding to the movement amount of each elevator determined by the third means. Actuator And a fourth means for controlling each driver so as to drive the controller. 4. The elevator according to claim 1, wherein the second unit is configured to specify a lift located farthest from the designated destination position based on the position of each lift determined by the first unit. Based on the position and speed obtained by the first means with reference to the position of the elevator specified by the fifth means, a target position to be reached by the start time of the next control cycle of each elevator is determined. The control device for a lifting system according to claim 3, further comprising: a sixth means for determining.