NL7809720A - BRIDGE CRANE CONTROL. - Google Patents

Description

, 1 - · ν Η D Ηο / ΗΗ, 75 - * ~: "'-" ι,. ι: i. ·· iv; -. * f. ' Heemaf B.V. in Hengelo. . --- n,

Bridge crane steering

The invention relates to a method and device! for controlling the cat's movement and height! i from the hoist of a gantry crane.

Systems are known in which the swing angle b of the hoist is measured and on this basis the movement of the cat varies, such that at the end position the swing angle of; the hoist is 0 or nearly 0.

Furthermore, it is possible to record certain movement patterns based on experience, depending on the distance to be covered and to execute these automatically. 1 The drawback of the first mentioned rule j method is that it is difficult to measure the pendulum angle, l! while the control system is also complicated. The second mentioned method has the drawback that the course of the movement is not optimized, since a choice has to be made from a number of existing patterns.

The object of the invention is to provide a control method in which a load can be brought from the hoist to the desired target in the shortest possible time and with the smallest possible residual 2-h swing using a bridge crane. ,:

This is achieved according to the invention by starting from the starting position and the desired end position of the cat and the hoist, the maximum permissible hoist lengths during transport, repeated for different acceleration values using the angular momentum law:

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dt y dt at y 'y dt ^ where ^ = pendulum angle with respect to the vertical, y = length of the hoist, g «acceleration of gravity and 30 x = cat position, calculation of the residual runout 7809720 2 ~ * r • hoist at the end position, determining the acceleration by comparing the results, with the remainder; sway is minimal and feeding of the measured displacement

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acceleration value to the control mechanism of the bridge-5 crane.

In the proposed method, the desired movement pattern can be performed prior to the control of the bridge crane. : be optimized, assuming that those calculations can be performed quickly, so that the waiting time lu is negligible. The operating system according to the; the invention is an open, that is to say not feedback, scheme. Prior to the calculation, a number of acceleration values can be excluded on the basis of the maximum permitted hoist lengths during transport and the distance to be traveled by the cat. This gives the advantage that only a limited number of calculations have to be carried out, since those acceleration values that do not qualify after all are a priori excluded. This can be achieved in that the acceleration values to be applied are divided into two groups, one of which is used at maximum allowable hoist lengths and the distance to be traveled by the cat below and one at maximum allowable hoist lengths and the distance to be covered by the cat. place distance above chosen values.

It will be clear that in order to be able to perform a large number of calculations in the shortest possible time, use is preferably made of electronic means. To this end, according to the invention, an apparatus for carrying out the above method is proposed, characterized by an analog simulation circuit for simulating the differential equation:

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a generator circuit for generating and supplying various pulse signals to the simulation circuit, one connected to the output of the simulation circuit; - 3- * * *! comparison circuit for each time comparing its output signals with previous output signals and determining the output signals as low as possible (f (t), a memory connected to the comparison circuit and the generator-5 circuit for storing the at; fit impulse signal and a circuit connected to the memory for generating control signals for the bridge crane It is further proposed to use an exclusion circuit connected to the simulation circuit and the generator circuit 10 for the purpose of the maximum permissible hoist lengths excluding undesired impulse signals formed by the generator circuit j 'during transport. Since the signals obtained are analog signals, the control signals are applied to the bridge crane via a jlb integrator circuit.

The invention is elucidated on the basis of a block diagram according to the accompanying drawing. J

In the block diagram, xQ is the starting position! of the cat, yQ the start length of the hoist, y ^ the desired '20 length of the hoist, x ^ the end position of the cat, Ϋο the start speed of the hoist movement, K ^, K ^, |

Kr the limit values of the area where the hoist should remain outside i, a (t) the acceleration value, y (t) the instantaneous hoist length and if it) the pendulum angle with respect to the vertical. |

The initial conditions are entered in the i memory 2. This concerns the data xQ, yQ, y ^, x ^, j '"yQ, Kh, Κχ, Kr. Then a start command Sx j is given, which activates the control circuit 1. | As a result of this, the said initial conditions are recorded in the memory 2. On the basis of the initial data, the selection circuit 10 decides whether the so-called short or long program should be executed. This choice is determined on the basis of the path to be traveled by the cat and the expected course of the length of the hoist.

When the short program is selected, only those acceleration values are generated that fit a ...... j 7809720 -4 - ar r short-term transport .. The result of the selection is reflected by! -........ ~ -; - the circuit 10. communicated a signal ^; to the control circuit 1. By means of the signal, the control circuit 1 controls the generator 3, which 5 successively forms a number of acceleration values a (t). It should be noted that only meaningful values for a (t); generated. Acceleration values that the drive:; cannot realize are not excited. Each acceleration signal is applied to the circuit 4 # which further 10; received the signals K ^, and Kr from the circuit 2. On the basis of these data, circuit 4 forms:; the signals y (t) and £ (t), which is the lifting speed of the i; hoist as a function of time. The intended signals are applied to the simulation circuit 5, | which is an electronic model of the hoist and in which "i! ! known way by means of operational amplifiers,

choice of resistors, inductors and capacitors I.

! the differential equation; + 1. &. SJL + 3. sin_ ip = ssaJt. «F * dt" * y dt dt yy dn 2u is simulated. As a result, the circuit 5 i produces the pendulum angle ψ (t) and the angular velocity ψ (t). The latter signals are applied to the evaluation circuit 6. This evaluation circuit 6 compares the supplied values with the previously generated values. 25 selects the hitherto most desired value therefrom and supplies these signals to the memory 7. It is noted that j is the most desired value, whereby the calculated residual value of the runout is minimal The associated value of the acceleration is stored from the generator 3 in the memory 7. After the optimum value has been obtained in this way, the drive generator circuit 8 is activated by means of the signal, which takes the optimum value from the memory 7 and delivers the generated control signal to the integrator 9. The drive 3b of 3rd bridge crane is controlled from the integrator 9.

78 0 9 7 2 0 "

Claims (7)

1. Method for controlling the movement of the cat and the length of the hoist of a gantry crane, characterized by, starting from the starting position and the desired end position of the cat and the hoist, the maximum permissible during transport hoist lengths repeated for different acceleration values using the angular momentum law: +1. èl. + a -22Μί- + ώ,! dt ^ y dt dt y * y dt * 'where = pendulum angle with respect to the vertical, y = length of the hoist, g = acceleration of gravity! and x = position cat, calculating the residual runout of the j: hoist at the end position, determining that acceleration by comparing the results, with the residual; sway is minimal and feeding the measured displacement; acceleration value at the control mechanism of the bridge! crane. ; Method according to claim 1, characterized in that the acceleration values are selected on the basis of the maximum permissible hoist lengths during transport and the distance to be traveled by the cat. Method according to claim 2, characterized in that the acceleration values to be used are divided into two groups, one of which is used at maximum permissible hoist lengths and the distances to be covered by the cat; down position and one at maximum permissible hoist lengths and the distance to be traveled by the cat above selected values. Apparatus for carrying out the method according to claims 1-3, characterized by an analog simulation circuit for simulating the differential equation: <≤ £ + 2. &. <L1 + 2 sia. «. ££ 241. afx dt ^ y dt dt y y dt * a generator circuit for generating and on the Simula- 7809720 f · - b - t · ~ t switching input and _ of various impiils signals, connected to the output of the simulation circuit! i! comparison circuit for each time comparing the output signals thereof with previous output signals and | determining the output signals with a low possible (t), one with the comparison circuit and the generator; circuit connected memory for storing the pulse signal associated with j. the (t) and a pulse with the memory t. connected circuit for generating control signals for, the bridge crane. t 5. Device as claimed in claim 4, characterized by a exclusion circuit connected to the simulation circuit and the generator circuit for the purpose of operating on the basis of the i! to exclude maximum permissible hoist lengths during transport j from undesired impulse signals generated by the generator circuit j. j 6. Device as claimed in claims 4-6, characterized in that the control signals are supplied to the bridge crane via an integrator circuit. ! * »'I {ί} ** | ί - ·! ! j i i j i j | «I {i 78 0 9720 ................- / / ύ ^ -1 I —— I Π 'TTh Γ | -...... ^ 5 / | ? ££ =: ξ— ^ 5λ>? D ^ —► L _ * = YO ^ -► 1 * ΖΣ-Ζ ΤΓΤΤ KP = £ yft) yU) j * j 1 'πΠΊΓj- fit), γ ^^ 6 - -►, 7 / I ..... I 1 '-J rs4 _fZ —............. *' —1 iWV- ^ tioiq ^ jsr 7809720