JPH0244757B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a steady rest control device for a suspended crane;
For example, the present invention relates to a steady rest control device for a suspended crane that performs cargo handling work by moving a trolley such as an overhead traveling crane. FIG. 1 shows a block diagram of an example of a conventional steady rest control device for a suspended crane. The speed control device 10 includes a differential circuit 10a that takes the deviation between the corrected desired speed value _Vd1 and the detected speed Vm of the motor, a compensator 10b, a main amplifier 10c composed of a thyristor amplifier or a transistor amplifier, and a motor 10.
d, and a speed detector 10e. The trolley device 12 transfers the power of the electric motor 10d to the trolley 1.
2a has a gear mechanism 12b. Deflection angle/
The angular velocity detector 14 detects the swing angle θ of the suspended load 12c.
The angular velocity θ is detected and converted into voltage as an electrical quantity.
A speed correction amount generation circuit 16 generates a speed correction amount corresponding to the rope length l, load swing angle θ, and angular velocity θ.
The deflection angle prevention control start timing generating circuit 18 receives the detection value of the speed detector 10e and the detection value of the deflection angle/angular velocity detector 14 as input, and determines whether or not to execute the deflection angle prevention control. The gate circuit 20 is the deflection angle prevention control start timing generation circuit 1
Upon receiving the output signal No. 8, the speed correction amount of the speed correction amount generating circuit 16 is supplied to the adding circuit 22.
The adder circuit 22 inputs the speed correction amount and the speed desired value of the speed pattern generator 24, and supplies the corrected speed desired value Vd ₁ to the difference circuit 10a. The conventional steady rest control device for a suspended crane has the above-mentioned structure, and its operation will be explained next. When the trolley 12a is accelerated or decelerated, the suspended load 12c vibrates. This load swing angle θ and angular velocity θ are the swing angle and
The angular velocity is detected by the angular velocity detector 14, the detected value is multiplied by an appropriate return gain, and the detected value is sent to the velocity control device 1 via the velocity correction amount generation circuit 16, gate circuit 20, and addition circuit 22.
This method automatically controls the load to return to zero and reduce load swing, and is called a feedback control method. However, this method has the disadvantage that when trying to suppress load swing, the operating efficiency of the crane decreases and the control time is long. Furthermore, in addition to the conventional method shown in FIG. 1, a crane to be controlled is modeled, travel conditions are given, and a speed pattern for achieving steady rest control is determined in advance using digital simulation techniques. In actual control, there is a program control method in which several types of control solutions are prepared from the simulation results and the trolley speed is controlled using the control solution corresponding to the running conditions. This method has drawbacks such as the inability to use the same speed pattern when the traveling conditions of the crane to be controlled change, that is, lack of flexibility, and the inability to shorten the time required for control. In addition to the above, a research report on crane steady rest control is published by Kenichi Yoshimoto (Automation of Ore Unloader) Machinery Research Vol. 23, No. 1, 1971, pp. 40-44.
There is a page. In this report, mathematical considerations are made to simultaneously achieve the positioning of the trolley and the steadying of the suspended load in the shortest possible time. However, here, we mainly analyze the steady rest in the acceleration/deceleration section, and we classify the analysis into four types of speed patterns depending on the travel distance L, but the travel conditions (rope length L, travel Distance L, maximum acceleration αmax, maximum velocity Vmax) were not considered, so there were drawbacks such as the fact that it did not provide sufficient design guidelines when designing an actual control system. The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a steady rest control device for a suspended crane that has high operational efficiency and is flexible enough to accommodate any crane running conditions. It is in. In order to achieve the above object, the present invention provides an input device for inputting crane running conditions according to the travel distance, maximum speed, maximum acceleration, and rope length of the trolley, and A calculation device that calculates the travel time of the crane for a plurality of prepared speed patterns, and a speed pattern that allows the crane to travel in the shortest time for the above travel conditions from among the multiple speed patterns based on the calculation results. It is equipped with a speed pattern selection device, and a speed control device that controls the trolley speed based on the speed pattern selected by the speed pattern selection device to stabilize the crane, and calculates the traveling time of each crane. For the speed pattern, the travel time in the acceleration section is determined based on the maximum speed and maximum acceleration of the trolley, and the travel conditions according to the rope length, so that the trolley speed reaches its maximum value and the load swing is zero at the end of the acceleration section. calculate,
Furthermore, at the end of the deceleration section, that is, when the trolley stops, the time and deceleration in the constant speed section are determined based on the maximum speed and maximum acceleration of the trolley, the rope length, and the running conditions according to the travel distance, so that the load swing is zero and the travel distance is satisfied when the trolley stops. The feature is that the time in the interval is calculated and found. Hereinafter, preferred embodiments of the present invention will be described based on the drawings. FIG. 2 is a block diagram of the apparatus of the present invention in which the same parts as in FIG. 1 are given the same reference numerals.
Portions that are the same as those in the figures are the same as those described above, so their explanation will be omitted. In FIG. 2, the input device 26 includes rope length l, traveling distance L, maximum acceleration αmax, which is a constraint condition of the crane system, and maximum speed.
Running conditions such as Vmax are input, and the output side is an evaluation standard calculation device 28 and a speed pattern calculation device 3.
0 and the load swing angle calculation device 33. The speed pattern calculation device 30 is composed of speed pattern calculation devices 30a to 30e corresponding to, for example, five types of speed patterns 1 to 5, and calculates speed patterns (acceleration switching time and It calculates the amount of change in acceleration), and each speed pattern calculation device 30a to 3
The output of 0e is connected to the evaluation standard calculation device 28. The load swing angle calculation device 33 calculates speed pattern 1.
Load swing angle calculation devices 33a to 33e corresponding to ~5
A speed pattern calculation device 30a
From the acceleration switching time and acceleration change amount, which are the outputs of ~30e, for each speed pattern,
That is, the load swing angle θ is calculated while the trolley is moving, including the acceleration section, constant speed section, and deceleration section. The load swing angle θ is calculated using equations (4) to (7), which will be described later, for example, in speed pattern 5, immediately before the trolley is operated. Note that other speed patterns can also be found by applying the state transition method and performing similar analysis. This output is also connected to the evaluation criterion calculation device 28. Evaluation criteria calculation device 28
inputs the acceleration that is the output of the speed pattern calculation device 30, the amount of change thereof, the acceleration switching time, the running time, and the load swing angle during operation that is the output of the load swing angle calculation device 33, and calculates five types of speeds. Each speed pattern is evaluated from among the patterns based on travel time, load swing angle during travel, acceleration change amount, etc., and its output is connected to a speed pattern selection device 32. The speed pattern selection device 32 selects a speed pattern suitable for the traveling conditions of the crane to be controlled based on the evaluation result of the evaluation standard calculation device 28, and its output side is connected to the speed pattern generation device 2.
It is wired to 4. Speed pattern generator 24
generates the trolley speed pattern selected by the speed pattern selection device 32. The embodiment of the present invention has the above configuration, and its operation will be explained below. Focusing on the trolley speed, crane operation consists of an acceleration section, a constant speed section, and a deceleration section as shown in Figure 3, and these basic operations are repeated to carry out cargo handling and transportation. It is desirable to shorten the cycle time. Therefore, acceleration and deceleration are often repeated in the acceleration section and the deceleration section. Therefore, optimal operation of the crane means determining the acceleration switching time that minimizes the cycle time, or in other words, determining the speed pattern. On the other hand, various requirements are made depending on the purpose and use of the crane. For example: (1) Shorten cycle time as much as possible. (2) Drive safely. (3) Control using the simplest control method possible. However, it is difficult to optimize the operation of a multi-purpose crane such as the one described above. Therefore, the present invention prepares five types of speed patterns as shown in Fig. 3, selects a speed pattern suitable for the purpose/application and running conditions of the crane to be controlled, and performs pattern operation in the selected pattern. It is something. The characteristics of each speed pattern shown in FIG. 3 are as follows. Speed pattern 1: This is a simple trapezoidal wave pattern, and compared to other patterns, it is characterized by allowing the suspended load to vibrate in the constant speed section. Speed pattern 2: This is a well-known basic trapezoidal wave pattern that accelerates and decelerates the trolley in a time that is an integral multiple of the vibration period of the suspended load. Speed pattern 3: This is a speed pattern in which a constant speed section is once provided in the acceleration/deceleration section, the trolley is accelerated → constant speed → acceleration → desired speed, and the load swing in the constant speed section is zero. Speed pattern 4: Optimization of acceleration/deceleration sections. Speed pattern 5: This is a speed pattern in which the vehicle decelerates once during the acceleration section and accelerates once during the deceleration section. Speed pattern 4 above is the optimal crane operation with optimized acceleration/deceleration sections, and this is a research report by "Kanai, Mita (optimal crane operation method) 21st Automatic Control Union Lecture Preprint" There is. The optimal operation of the crane will be considered below for each speed pattern, but first, the optimal operation of the crane will be analyzed for speed pattern 5. Other speed patterns can be analyzed using the same concept, so only the results will be shown. Considering the operating efficiency of the crane, it is recommended to set the trolley speed at the maximum speed in the constant speed section, and considering the safety at the site, it is necessary to make the load swing in the constant speed section zero (θ=θ〓
= 0) is desirable. Therefore, focusing on the acceleration/deceleration section of the trolley, consider setting the trolley speed to the maximum speed Vmax in the shortest time and making the load swing at that time zero. If the load swing is zero at the end time of the acceleration section, the trolley is not accelerated or decelerated during the constant speed section, so the load swing is zero. In the deceleration zone, the boundary conditions are simply reversed from those in the acceleration zone, so the speed pattern is symmetrical to that in the acceleration zone. Therefore, we will focus our analysis on the acceleration section. Further, the time of the constant speed section may be determined so as to satisfy the driving conditions. Here, we make the following three assumptions. (1) The length of the rope remains constant during travel. (2) Runout friction is so small that it can be ignored. (3) The load swing angle is sufficiently small. By applying the time axis transformation such that τ = ωt, the trolley speed,
The equation of motion, boundary conditions, and restraint conditions regarding load swing are as follows:

【table】

Claims (1)

[Claims] 1 Trolley travel distance, maximum speed, maximum acceleration,
an input device for inputting crane running conditions according to the rope length; a calculation device for calculating acceleration switching times for multiple speed patterns prepared in advance based on the input traveling conditions; a speed pattern selection device that selects a speed pattern that allows the crane to travel in the shortest time for the above-mentioned travel conditions from among the speed patterns; and a speed that controls the trolley speed based on this speed pattern to stabilize the crane. The calculation of the acceleration switching time of the crane is based on the maximum speed of the trolley and the maximum speed so that the trolley speed reaches the maximum value and the load swing becomes zero at the end of the acceleration period for each speed pattern. The acceleration switching time in the acceleration section is calculated from the acceleration and the above crane running conditions, and the acceleration switching time is calculated according to the above crane running conditions and the traveling distance so that the load swing is zero and the running distance is satisfied at the end of the deceleration section, that is, when the trolley stops. A steady rest control device for a suspended crane, characterized in that an acceleration switching time in a constant speed section and an acceleration switching time in a deceleration section are calculated and determined from running conditions.