An experimental study of the efficiency of optimal control for lifting machines

The article is devoted to the synthesis of optimal speed performance control, in which the Pontryagin maximum principle and the phase-plane method are used to search for switching points of the relay control function. A crane trolley model and computer control system, able to implement the automatic movement of the trolley according to the optimal laws, were developed. The conducted experimental study allowed us to establish that the operating cycle of the traveling mechanism can be reduced by 1.5-3.1 times using optimal speed performance control

Payload Oscillations Minimization via Open Loop Control.

The results of tests of payload oscillations, forced by linear control function which allows to minimize payload sway after acceleration phase and after overhead crane stopping are presented in this paper. The analysis of solution of this problem has been carried out. The algorithm of operation for real drive system which takes into account the possibilities of driving of an overhead crane is also presented. The impact of inaccuracies of measurement of the ropes length on minimizing a displacements of payload during the duty cycle is shown as well. The correctness of the method is confirmed by results both simulation and experimental tests

A solution of a problem of optimal crane control using the controllability function method

Продуктивність, надійність а також зручність експлуатації кранів багато в чому залежать від коливань підвішеного на гнучкому підвісі вантажу. Одним з важливих резервів підвищення ефективності роботи крана є оптимізація перехідних режимів руху вантажного візка (розгін/гальмування). У роботі розглядається модель руху "візок – вантаж" для мостового крана в задачі оптимального керування. Показано, що вихідна задача переміщення вантажу з деякої початкової точки в задану точку, в котрій система буде знаходитися в стані спокою, за кінцевий час та при наявності обмежень на керування, еквівалентна задачі локальної нуль-керованості для цієї системи. Представлено конструктивне рішення цієї задачі з використанням метода синтезу інерційних керувань – розвиток методу функції керованості. Досліджується задача побудови обмеженого керування, яке переводить систему з однієї заданої точки в іншу. Приводяться і обговорюються результати застосування у вигляді декількох різних алгоритмів розв’язання задачі за допомогою методу функції керованості, а також результати роботи програм, які реалізують ці алгоритми, і аналіз труднощів, що виникають, та шляхів їх вирішення.Productivity, reliability, as well as ease of crane operation largely depends on the vibrations of cargo suspended on a flexible rope. One of the main reserves to improve the crane efficiency is transient mode optimization of the trolley movement (acceleration/deceleration). A "trolley – cargo" movement model that represents operation of an overhead crane in tasks of optimal control are considered. It is shown that an initial task of cargo movement from a certain initial point to a given point, at which the system would be at the quiescent state by a finite time and with control constraints, is equivalent to a task of local zero-controllability for this system. A practical solution of this task is presented by using the inertial control synthesis method, that is evolution of the controllability function method. The task of receiving bounded control that transfers a system from one given point to another are studied. Results of application in the form of several different algorithms for solving the task using the controllability function method, as well as results of programs implementing these algorithms, and an analysis of emerging difficulties and ways of its overcoming are presented and discussed

Dynamic analysis of movement of carriage hoisting crane with a displaced center of mass cargo for grips

Наведено динамічний аналіз руху системи, що складається з візка, захватного пристрою і вантажу зі зміщеним центром мас відносно захватного пристрою в процесі розгону. При цьому пуск крана здійснюється на природній механічній характеристиці електродвигуна. Вихідні дані для проведення динамічного аналізу руху системи «візок – захватний пристрій – вантаж» використані з крана ККУ – 10, що оснащений грейферним захватом на гнучкому підвісі з пачкою колод.In the article the dynamic analysis of motion of the system consisting of a carriage, grip and cargo with a displaced center of mass over the gripper during acceleration is presented, starting of crane being the natural mechanical characteristics of the electric motor. The data input for the dynamic motion analysis of system «carriage – grip – cargo» the crane KKU – 10, which is equipped with a grab on a flexible hanger with a bundle of logs, is used. Mechanical characteristics of the induction motor (MT 112-6) carriage drive, is described by the Kloss, equation linking the electromagnetic torque with sliding Basing on the developed dynamic model equations of motion are obtained, which are constructed using the Lagrange method of second order. These equations represent a system of nonlinear differential equations of second order, which are solved by the numerical methods. When constructing dynamic model of the movement of carriage with a cargo it is assumed that all elements of the crane carriage are moving in a vertical plane, all elements of carriage are perfectly solid, except the grip, that has an elastic connection with cargo and cargo rope, which deviates from the vertical. The linear coordinates of the center of mass of carriage х and angular coordinates deviation from the vertical rope cargo ψ and axis of timber φ are chosen as the generalized coordinates of the developed dynamic model. The graphs of change kinematic characteristics of carriage, grip and cargo are presented. The change of the driving torque of the drive motor during acceleration is investigated. The results testify that after acceleration of carriage significant variations in gripping device and cargo appear. It results in the decrease of productivity and reliability of the crane, as well as to overload of the motor and its control device. Furthermore, minor variations are observed during the steady movement of the carriage with cargo, which then disappear

The controllability function method

The paper is devoted to the control problem for the movement of an overhead crane with the use of a dynamic model in the form of "trolley - cargo" mechanical system and the driving force as a control parameter. To solve the system of differential equations, which describe the movement of the system taking into account constraints for the control, the controllability function method is applied. The algorithm for solving the problem is described, a program is developed as well as difficulties, which occur while implementing the method, and ways of its solution are marked. Results of constructing the control and system trajectories are also provided as an example of the program work

X-56A Structural Dynamics Ground Testing Overview and Lessons Learned

The X-56A Multi-Utility Technology Testbed (MUTT) is a subscale, fixed-wing aircraft designed for high-risk aeroelastic flight demonstration and research. Structural dynamics ground testing for model validation was especially important for this vehicle because the structural model was directly used in the development of a flight control system with active flutter suppression capabilities. Structural dynamics ground tests of the X-56A MUTT with coupled rigid-body and structural modes provided a unique set of challenges. An overview of the ground vibration test (GVT) and moment of inertia (MOI) test setup and execution is presented. The series of GVTs included the wing by itself attached to a strongback and complete vehicle at two mass conditions: empty and full fuel. Two boundary conditions for the complete-vehicle test were studied: on landing gear and suspended free-free. Pitch MOI tests were performed using a compound pendulum method and repeated with two different pendulum lengths for independent verification. The original soft-support test configuration for the GVT used multiple bungees, resulting in unforeseen coupling interactions between the soft-support bungees and the vehicle structural modes. To resolve this problem, the soft-support test setup underwent multiple iterations. The various GVT configurations and boundary-condition modifications are highlighted and explained. Lessons learned are captured for future consideration when performing structural dynamics testing with similar vehicles

Nonlinear Dynamic Modelling and Analysis of a 3-D Overhead Gantry Crane System with System Parameters Variation

Overhead cranes are widely used in industry for transportation of heavy loads. The natural sway of crane payloads is detrimental to safe and efficient operation. However, the crane acceleration, required for motion, always induces undesirable load swing. This paper presents dynamic modelling of a 3-D overhead gantry crane system based on closed-form equations of motion. The Lagrangian method is used to derive the dynamic model of the system. A dynamic model of the system incorporating payload and rope length is developed. Then the effects of payload and rope length on the response of the system are discussed. Extensive results that validate the theoretical derivation are presented in the time and frequency domains