Semi‐active modal control of structures with lockable joints: general methodology and applications

Abstract

Summary In this study, a novel modal control strategy by means of semi‐actively lockable joints is proposed. The control strategy allows for a directed flow of energy between vibrational modes, which makes it suitable not only for vibration attenuation purposes but also for energy scavenging driven by electromechanical energy harvesters. The proposed control strategy is an extension of the prestress‐accumulation release (PAR) technique; however, it introduces also new concepts that increase the efficiency of the overall control system. Contrary to the PAR, the proposed method requires measurement of both strains in the vicinity of the semi‐active joints and translational velocities that provide global information about system behavior. The latter aspect requires the control system to be organized within a hierarchical feedback architecture. The benefit from this higher complexity of the control system is its better performance compared to the PAR. The proposed semi‐active modal control not only attenuates structural vibration faster, but it also achieves this goal with a smaller number of switches implemented in the joints. The effectiveness of the proposed methodology has been demonstrated on structures equipped with two lockable joints. Two practical examples have been investigated: one employs the concept of vibration‐based energy harvesting for a two‐story frame structure, while the second one reduces vibration of an eight‐story frame structure subjected to kinematic excitation.

Semi-Active Sliding-Mode Control for Local Mitigation of Structural Vibrations by Means of on/Off Nodes

“…The proposed control approach is tested using a model of a six-story shear-type structure shown in Figure 2. The geometric and material characteristics of the structure are similar to those in [21]. Each story measures 0.4×0.4 m, and each beam has a cross-section of 8×10 mm.…”

“…However, these nodes can also be utilized to trigger the transfer of vibrational energy to high-order modes, which are more effectively damped by standard material damping mechanisms compared to low-order modes [19]. The control laws involved are either simple heuristics [20] or more formal and explicitly aimed at modal energy transfer [21]. These formulations focused on energetic measures of structural vibrations.…”

“…However, energy is a suitable overall measure of the severity of structural vibrations but often does not correlate well with local vibration amplitudes. Therefore, this contribution presents an approach inspired by [21] that focuses on minimizing displacement in a particular degree of freedom (DOF). The sliding-mode control formulation is employed [22], and the sliding hyperplane is defined in the configuration space by zero displacement in the target DOF.…”

Influence of Noise in Computer-Vision-Based Measurements on Parameter Identification in Structural Dynamics

“…Thus, they are treated as rigid bodies. More details about these joints can be found in [ 42 , 43 , 44 ]. Steel rectangular beam profiles are connected with the joints via uncertain bolted connections whose stiffness is to be identified.…”

Reinforcement learning‐based control to suppress the transient vibration of semi‐active structures subjected to unknown harmonic excitation

“…Nevertheless, due to the high computational complexity of the search for the optimal solution, they are mostly restricted to applications in linear structures with active force control actuators. The recent trend in structural control promotes the use of semi‐active devices (Cundumi & Suárez, 2008; Gutierrez Soto & Adeli, 2019; Naderpoor Shad & Taghikhany, 2021), in particular, those based on intelligent materials (Ostrowski et al., 2021; Szmidt et al., 2019) that offer robust, energy‐efficient operation, and relatively easy deployment. However, semi‐active devices introduce nonlinearities, which in the case of multi–degree‐of‐freedom systems result in highly complex optimal control problems.…”