JPH04243796A - Speed control method for crane - Google Patents

Abstract

PURPOSE:To minimize a crane travel speed without causing any cargo collapse due to selection between acceleration and deceleration. CONSTITUTION:A crane can travel at a constant speed as well as at speeds v1, v2 and v3. When the crane is unable to accelerate up to the high speed v1, due to a small travel distance, the speed is increased up to v4 as near the high speed v1 as possible. Then, the crane travels at the constant speed v4 for a while, and then begins to decelerate. As a result, the travel time can be made shorter than the case where the crane is required to travel at the intermediate speed v2 along a long distance.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the speed of a crane that moves up and down and travels in front of an automated warehouse to deliver goods, and more particularly to a method for controlling the speed of a crane that can shorten the travel time of the crane. .

0002

BACKGROUND OF THE INVENTION At present, the speed control of cranes when lifting, lowering, and traveling is performed by so-called trapezoidal control.

FIG. 2 is a diagram showing the speed-time relationship under trapezoidal control in the travel of a commonly used crane platform.

[0004] In this example, the traveling platform is v1 (high speed)
, v2 (medium speed), and v3 (low speed). For example, v1 is 180m/min
, v2 is a speed of 60 m/min, and v3 is a speed of 10 m/min. The traveling platform accelerates from 0 to t1, runs at high speed at a constant speed v1 from t1 to t2, decelerates from t2 to t3, runs at a constant speed v2 from t3 to t4, and runs at a medium speed from t4 to t5. The vehicle travels at a low speed from t5 to t6 at a constant speed v3, and from t6 to t7 the vehicle decelerates and stops at the target position. The step-by-step deceleration process uses a position determining means such as a combination of a photoelectric sensor and a shield plate to detect the stopping position while driving at medium to low speeds, and to arrive at the exact stopping position. This is to stop it.

In such trapezoidal control, from 0 to t
The acceleration travel time from t2 to t7 and the deceleration procedure from t2 to t7 can hardly be changed. Therefore, from 0 to t
The area L1 indicating the distance traveled from t2 to t7 is approximately constant. Changing the mileage is done at high speed
By expanding or contracting the constant speed traveling time at t1
This is done by changing the area L2 of the rectangular portion from t2 to t2. The constant speed travel time at high speed v1 is calculated by the crane controller.

[0006]

[Problem to be solved by the invention] Mileage distances L1 and L2
If the distance is greater than the sum of L1 and L2, the traveling as described above is performed, but if the traveling vehicle travels a short distance less than the sum of L1 and L2, the traveling platform cannot reach the high speed v1. Can not. In this case, according to the trapezoidal control, the traveling speed changes as shown, for example, from ta to t7. The traveling platform accelerates from ta to tb, and travels at medium speed v2 from tb to t4. Also, according to so-called triangular control, acceleration is performed from tc to td, and t
The vehicle is decelerated from d to t3.

Therefore, it is clear that triangular control is preferable in terms of shortening travel time for efficient conveyance, but if deceleration is started in the middle of acceleration during td, the platform will shake. , causing the loaded items to collapse. For this reason, conventionally, in such cases, trapezoidal control with less shaking and vibration at the start of deceleration has been performed at the expense of travel time. However, according to trapezoidal control, for example, when there is a large speed difference between high and medium speeds,
In cases where the travel distance is so short that it cannot reach medium speed V2 and the vehicle must travel a long distance at low speed V3, the time from ta to t7 may be considerably longer than the time from tc to t7. There was a desire to improve work efficiency in this regard.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a crane speed control method that can shorten travel time without causing the cargo being transported to collapse.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a speed control method for a crane, which controls the speed of lifting/lowering/travelling of a crane. The speed control method of the crane is configured such that the crane moves at a constant speed during the transition from the acceleration state to the deceleration state when the speed is so short that it cannot reach the maximum speed of the crane.

0010

[Operations and Effects] Since the present invention has the above-mentioned structure, the following operations and effects are achieved.

The crane speed control method according to the present invention includes:
This applies when the distance to be traveled is so short that the maximum speed of the platform/traveling platform cannot be reached. In this case, the elevating platform/traveling platform accelerates, and then starts decelerating after having time to move at a constant speed below the maximum speed. Although the constant speed is less than the maximum speed, it is clear that the travel time can be shortened if the speed is as close to the maximum speed as possible. In this regard, it is also clear that it is preferable that the time for moving at a constant speed be as short as possible, but long enough to avoid violent shaking or vibration of the platform.

Therefore, according to the crane speed control method according to the present invention, although the crane is basically trapezoidal controlled, elements of triangular control are incorporated to shorten travel time as much as possible and achieve efficient transportation. control can be realized.

[0013]

[Embodiment] The embodiment shown in the drawings will be explained below.

FIG. 1 is a diagram showing the relationship between the speed of a crane traveling base and time according to an embodiment of the crane speed control method according to the present invention.

In the figure, if the distance to be traveled is sufficiently long, the crane platform accelerates in the same way as in the conventional conventional trapezoidal control, and moves in a sequence of high-speed travel and deceleration.

A crane to which the crane speed control method according to the present invention can be applied can run at constant speeds such as a maximum speed v1, a medium speed v2 for deceleration procedures, and a low speed v3.
It can run at a constant speed.

Therefore, according to the conventional trapezoidal control, since the maximum speed cannot be reached, the distance where speed control is performed from ta to t7 is changed to speed control from te to t7. That is, the traveling platform accelerates from te to tf, reaches speed v4, travels at constant speed v4 until tg, and then starts decelerating. Therefore, travel time can be shortened. The constant speed v4 and the traveling time at the constant speed between tf and tg are determined by calculations of the crane control device. The speed is as close to the maximum speed as possible,
In addition, the time is calculated to be as short as possible without causing the articles placed on the lifting platform to collapse due to shaking or vibration.

According to this speed control method, when the vehicle travels a distance so short that it cannot reach the medium speed v2, it reaches the destination in a short time at a speed from th to t7. If the speed of movement of the same distance is controlled by conventional trapezoidal control, the traveling platform can only accelerate to the low speed v3, so it has to travel from ti to t7, which takes a very long time.

As described above, according to the crane speed control method of this embodiment, when moving a short distance where the crane cannot travel at the maximum speed, the cargo loaded on the lifting platform will not collapse. Since the movement can be carried out in a short time without any problems, it is possible to improve the efficiency of conveyance.

Although the embodiments of the present invention have been described above,
It goes without saying that the present invention is not limited to the above-mentioned embodiments, and can be modified as appropriate within the scope of the gist of the present invention.

For example, although the above-described embodiment was related to travel control of a crane traveling platform, it can also be applied to lifting and lowering of a lifting platform. Further, the speed is not limited to one in which a constant speed can be maintained steplessly, but the same effect can be obtained even if the speed can be changed in multiple stages.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a speed-time relationship showing an example of speed control according to an embodiment of the crane speed control method according to the present invention.

FIG. 2 is a diagram similar to FIG. 1 according to a conventional crane speed control method;

[Explanation of symbols]

v1 High speed v2 medium speed v3 low speed v4, v5 constant speed t time

Claims (1)

[Claims] Claim 1: A crane speed control method that controls the speed of lifting and traveling of a crane, and when the distance to be traveled is so short that the maximum speed of the lifting platform or traveling platform cannot be reached, A speed control method for a crane, characterized in that the crane moves at a constant speed while changing from a deceleration state to a deceleration state.