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

ADVANCED ANTI-SWAY CONTROL FOR OVERHEAD CRANES

This particular project focuses on a complex system whose dynamics are not very well understood and hence control designs are not straightforward. The project deals with the control of industrial overhead cranes. The project has the potential of bringing many rewards to industries, which are concerned with optimising lifting equipment performance. Such a system will allow these industries to save time and consequently costs as the volume of loaded and unloaded goods increases. Part of this project is to model the system surrounding the crane system and then design a suitable algorithm for load anti-sway purposes. The objective of this project is to design and implement an intelligent based controller that can be used to assist a crane operator in the difficult parts of the operation. The designed controller should give the appropriate control signal to the crane system such that the time taken to reach the target position is minimised with a zero sway angle at the destination. Earlier part of the project consisting of analysing and improving if required the existing 3-D mathematical linear and non-linear crane models. Two different models have been investigated: one with a constant cable length and the other with a variable cable length. The implementation of the controller is based on Fuzzy Logic Control (FLC). Two types of FLC have been used and compared the Fixed FLC and the FLC based on Adaptive Neuro Fuzzy Inference System (ANFIS). Heuristic approaches have been used for tuning the Fixed FLC. Data obtained from the Fixed FLC are then used for training ANFIS FLC. The results prove that it is possible to model an off-line expert fuzzy logic controller for an overhead crane. The controller achieved satisfactorily results for a constant and a variable rope length with minimal tuning than the fixed fuzzy method. Proposals for further work are also briefly discussed

Negative imaginary theorem with an application to robust control of a crane system

This paper presents an integral sliding mode (ISM) control for a case of negative imaginary (NI) systems. A gantry crane system (GCS) is considered in this work. ISM is a nonlinear control method introducing significant properties of precision, robustness, stress-free tuning and implementation. The GCS model considered in this work is derived based on the x direction and sway motion of the payload. The GCS is a negative imaginary (NI) system with a single pole at the origin. ISM consist of two blocks; the inner block made up of a pole placement controller (NI controller), designed using linear matrix inequality for robustness and outer block made up of sliding mode control to reject disturbances. The ISM is designed to control position tracking and anti-swing payload motion. The robustness of the control scheme is tested with an input disturbance of a sine wave signal. The simulation results show the effectiveness of the control scheme

Fuzzy sliding mode control of an offshore container crane

© 2017 A fuzzy sliding mode control strategy for offshore container cranes is investigated in this study. The offshore operations of loading and unloading containers are performed between a mega container ship, called the mother ship, and a smaller ship, called the mobile harbor (MH), which is equipped with a container crane. The MH is used to transfer the containers, in the open sea, and deliver them to a conventional stevedoring port, thereby minimizing the port congestion and also eliminating the need of expanding outwards. The control objective during the loading and unloading process is to keep the payload in a desired tolerance in harsh conditions of the MH motion. The proposed control strategy combines a fuzzy sliding mode control law and a prediction algorithm based on Kalman filtering for the MH roll angle. Here, the sliding surface is designed to incorporate the desired trolley trajectory while suppressing the sway motion of the payload. To improve the control performance, the discontinuous gain of the sliding control is adjusted with fuzzy logic tuning schemes with respect to the sliding function and its rate of change. Chattering is further reduced by a saturation function. Simulation and experimental results are provided to verify the effectiveness of the proposed control system for offshore container cranes

Estimating Sway Angle of Pendulum System Using Hybrid State Observer Incorporating Continuous and Discrete Sensing Signals

This paper presents the design of a hybrid state observer that estimates the sway angle in trolley systems with a pendulum, such as overhead cranes. In the system, sway angle signals detected by angular sensors are generally used for designing the anti-sway control of the pendulum or observing the pendulum state. By contrast, in this study, a linear state observer without sensors is applied to estimate the sway angle of the pendulum. The use of a standard asymptotic state observer leads to estimation error due to the system's nonlinearities and parametric errors. This paper proposes using a hybrid state observer design that combines discrete event sensing with a linear state observer. In the hybrid state observer, the estimation performance is improved by correcting the state of the system based on the discrete sway angle and angular velocity using discrete sensing. In addition, the parametric error of the pendulum length of the system is identified using the same hybrid setting. The effectiveness of the hybrid state observer and the parametric adaptation of the pendulum length are verified by conducting experiments using a downscaled prototype of a trolley system with a pendulum.publishedVersionPaid open acces