Modeling and control of 5-DoF boom crane

Automation of cranes can have a direct impact on the productivity of construction projects. In this paper, we focus on the control of one of the most used cranes, the boom crane. Tower cranes and overhead cranes have been widely studied in the literature, whereas the control of boom cranes has been investigated only by a few works. Typically, these works make use of simple models making use of a large number of simplifying assumptions (e.g. fixed length cable, assuming certain dynamics are uncoupled, etc.) A first result of this paper is to present a fairly complete nonlinear dynamic model of a boom crane taking into account all coupling dynamics and where the only simplifying assumption is that the cable is considered as rigid. The boom crane involves pitching and rotational movements, which generate complicated centrifugal forces, and consequently, equations of motion highly nonlinear. On the basis of this model, a control law has been developed able to perform position control of the crane while actively damping the oscillations of the load. The effectiveness of the approach has been tested in simulation with realistic physical parameters and tested in the presence of wind disturbances.Comment: the paper was published in 37th International Symposium on Automation and Robotics in Construction (ISARC 2020

Modelling and Control of a Knuckle Boom Crane

Cranes come in various sizes and designs to perform different tasks. Depending on their dynamic properties, they can be classified as gantry cranes and rotary cranes. In this paper we will focus on the so called 'knuckle boom' cranes which are among the most common types of rotary cranes. Compared with the other kinds of cranes (e.g. boom cranes, tower cranes, overhead cranes, etc), the study of knuckle cranes is still at an early stage and very few control strategies for this kind of crane have been proposed in the literature. Although fairly simple mechanically, from the control viewpoint the knuckle cranes present several challenges. A first result of this paper is to present for the first time a complete mathematical model for this kind of crane where it is possible to control the three rotations of the crane (known as luff, slew, and jib movement), and the cable length. The only simplifying assumption of the model is that the cable is considered rigid. On the basis of this model, we propose a nonlinear control law based on energy considerations which is able to perform position control of the crane while actively damping the oscillations of the load. The corresponding stability and convergence analysis is carefully proved using the LaSalle's invariance principle. The effectiveness of the proposed control approach has been tested in simulation with realistic physical parameters and in the presence of model mismatch.Comment: This paper has been accepted to International Journal of Control on March 29th 2021. arXiv admin note: text overlap with arXiv:2103.0250

Constraint Control of a Boom Crane System

Boom cranes are among the most used cranes to lift heavy loads. Although fairly simple mechanically, from the control viewpoint this kind of crane is a nonlinear underactuated system which presents several challenges, especially when con-trolled in the presence of constraints. To solve this problem, we propose an approach based on the Explicit Reference Governor (ERG), which does not require any online optimization, thus making it computationally inexpensive. The proposed control scheme is able to steer the crane to a desired position ensuring the respect of limited joint ranges, maximum oscillation angle, and the avoidance of static obstacles.Comment: The paper was published in 37th International Symposium on Automation and Robotics in Construction (ISARC 2020

Input shaping techniques for sway control of a rotary crane system

This paper investigates the performance of input shaping techniques for sway control of a rotary crane system. Unlike the conventional optimal controllers, input shaping is simple to design and cost effective as it does not require feedback sensors. Several input shapers were implemented and their performances were compared which are useful for future sway control designs. A nonlinear model of the system was derived using the Lagrange’s equation. To investigate the performance and robustness of input shaping techniques, zero vibration (ZV), zero vibration derivative (ZVD), zero vibration derivative-derivative (ZVDD) and zero vibration derivative-derivative-derivative (ZVDDD) were proposed with a constant cable length. Level of reduction of the payload sway is used to assess the control performance of the shapers. Simulation and real time experimental results have shown that ZVDDD with a sway reduction of 88% has the highest level of sway reduction and highest robustness to modeling errors as compared to other shapers

HYBRID POSITION AND VIBRATION CONTROL OF NONLINEAR CRANE SYSTEM

This paper presents comparative assessments of input shaping techniques using two different approaches, for sway reduction of cranes system. First, the shaper was designed at maximum load hoisting length while the second was designed at average load hoisting length. These were accomplished using curve fitting toolbox in MATLAB. In both case; Zero Vibration (ZV), Zero Vibration Derivative (ZVD) and Zero Vibration Derivative Derivatives (ZVDD) were designed. Average hoisting length (AHL) shapers performed better than the Maximum hoisting length (MHL) shapers. Proportional integral derivative (PID) was incorporated for position control. After successful implementation, Simulation results show that a precise payload positioning was achieved. AHL-ZVDD has superior performances in sway reduction and robustness.

Robust Control of Crane with Perturbations

In the presence of persistent perturbations in both unactuated and actuated dynamics of crane systems, an observer-based robust control method is proposed, which achieves the objective of trolley positioning and cargo swing suppression. By dealing with the unactuated and unknown perturbation as an augmented state variable, the system dynamics are transformed into a quasi-chain-of-integrators form based on which a reduced-order augmented-state observer is established to recover the perturbations appearing in the unactuated dynamics. A novel sliding manifold is constructed to improve the robust performance of the control system, and a linear control law is presented to make the state variables stay on the manifold in the presence of perturbations in unactuated dynamics. A Lyapunov function candidate is constructed, and the entire closed-loop system is proved rigorously to be exponentially stable at the equilibrium point. The effectiveness and robustness of the proposed observer-based robust controller are verified by numerical simulation results