Payload Pendulation Reduction Using a Variable-Geometry-Truss Architecture with LQR and Fuzzy Controls

Abstract

823420 We investigate the feasibility of a variable-geometry truss (VGT) based architecture for suppressing payload pendulations in ship-mounted cranes. The VGT assembly is conceived to be retrofitted onto the boom tip of ship-mounted cranes. A simplified planar model is developed. A control point along the cable hoisting the payload is constrained to move along a straight path with a given control input (acceleration) imparted via the actuators embedded in the VGT assembly. Control laws based on either linear quadratic or fuzzy control methodologies are developed in order to minimize an assigned cost functional. Their effectiveness is compared through extensive numerical simulations. The performance of the VGT architecture and associated control laws is analyzed when the crane is subject to the most severe combination of resonant excitations: a primary resonant roll excitation at the natural frequency of the controlled system, and a principal-parametric resonant heave excitation, both corresponding to sea state three and higher. The proposed strategy exhibits enough control authority over the system dynamics, greatly reducing the severe and undesirable resonant pendulations caused by the ship motions in a broad-band frequency range. Moreover, its disturbance-rejection capabilities are exerted with feasible control efforts, which are localized in the segment of the crane where they are needed.15( 2380 Cranes, variable-geometry truss, linear quadratic control, fuzzy control, nonlinear resonance, nonlinear active control

Distance Geometry in Active Structures

“…While the expansion of (12) leads to the triangular inequality involving the distances between P i1 , P i2 , and P i3 , (13) is nothing else than the tetrangular equality involving the six pairwise distances between P i1 , P i2 , P i3 , and P i4 . Note that the whole set of orientation constraints in (14) can not be fixed arbitrarily. Actually, it is possible to define a basis that determines all other orientations [55].…”

“…Such structures are mechanisms since their motions are typically achieved by means of actuated elements like revolute joints of variable-length bars. Due to their shape versatility, variable geometry structures have a myriad of potential applications including robot arms [20], hyper-redundant manipulators [10], flight simulators [54], payload vibration reduction [14], the manipulation of large payloads [52], morphing wings [16], space applications [30] or civil engineering structures [22]. The design of novel variable geometry structures rely on having a complete characterization of their valid configurations.…”

Closed-form position analysis of variable geometry trusses

“…This is why variable geometry trusses are sometimes considered a generalization of the serial/parallel robots [5]. Due to their exceptional stiffness to weight ratio, References [14] [15], [3] [16] [17] their structural simplicity, and their shape versatility, variable geometry trusses have a myriad of potential applications including robot arms [6], hyper-redundant manipulators [7], flight simulators [8], payload vibration reduction systems [9], tools to manipulate large payloads [10], morphing wings [11], space devices [12] or civil engineering structures [13]. The design of novel variable geometry trusses rely on having a complete kinematics characterization of their constituent cells.…”

Nonlinear interactions in deformable container cranes

“…A refined planar model was proposed in [13] where a double pendulum, two-dimensional (2D) model was adopted although neglecting the hoisting cables deformability. Planar (2D) pendulum-type crane models were also employed to study payload oscillations control via a nonclassical vibration absorber in [12], via an active open-loop strategy [20] or fuzzy controls using a variable truss geometry [8].…”