Chatter is an unfavorable phenomenon in turning operation causing poor surface quality. Active chatter elimination methods require the chatter to be detected before the control reacts. In this paper, a chatter detection method based on a coherence function of the acceleration of the tool in the x direction and an audio signal is proposed. The method was experimentally tested on longitudinal turning of a stock bar and facing of a hollow bar. The results show that the proposed method detects the chatter in an early stage and allows correcting control actions before the chatter influences the surface quality of the workpiece. The method is applicable both to facing and longitudinal turning.

Tower cranes are needed to move heavy objects safely around construction sites. In tower cranes, payload oscillations are a typical problem that can cause safety issues, especially if the crane is not operated by an experienced user. Depending on the system, there are different causes for oscillations, e.g., inertial forces from the crane movement or external forces, such as weather conditions. Hence, the selected control law for input tracking plays an important role to limit the oscillatory motion and to help the crane operator to prevent unwanted operations. In this paper, we study the slew control of a tower crane application from the viewpoint of reducing payload oscillations. Two different approaches are studied: open-loop control based on extrainsensitive input shaping and closed-loop swing angle control, based on the estimation of the hoist cable angle. The proposed control approaches are validated by running the developed control program against a multibody mechanics simulator containing a model of a Liebherr tower crane. The studied control laws are also evaluated using an experimental setup, which consists of a two-axis manipulator, inverters, and a programmable logic controller in which the studied control methods are implemented. The results from the multibody dynamics simulations and from the experimental setup are presented and evaluated from the viewpoint of crane operation.

Hybrid powertrains that combine electric machines and internal-combustion engines offer substantial opportunities to increase the energy efficiency and minimize the exhaust emissions of vehicles and nonroad working machines. Due to the wide range of applications of such powertrains, simulation tools are used to evaluate and compare the energy efficiency of hybrid powertrains for application-specific working cycles in virtual environments. Therefore, the accurate modeling of the powertrain components of a hybrid system is important. This paper presents an agile calculation tool that can generate realistic fuel consumption data of a scalable diesel engine. This method utilizes a simple efficiency model of the combustion and crank train friction model to generate the fuel consumption map in the operating area of a typical diesel engine. The model parameters are calibrated to produce accurate fuel consumption data in the initial phase of system-level simulations. The proposed method is also validated by using three real engine datasets, and the comparison of results is presented.

Application of energy storage (ES) in power distribution systems (PDS) of short sea shipping marine vessels is gaining ground. The main drivers are the increasing demand for higher energy efficiency and the decreasing costs of battery ES systems (BESS). The feasible chemistry and dimensioning of the BESS depend heavily on the vessel type, the PDS topology, and the load profile. Thus, no general rules for battery dimensioning that would fit all vessels can be presented, but the analysis must be performed by using an advanced modeling approach, which takes into account the abovementioned factors. This paper presents a modeling methodology for dimensioning marine vessel ES and hybrid PDS components. The methodology has been tested for two distinct vessels, a cruiseferry and an off-shore support vessel.

Traditional high-speed rotor configurations employing magnetic bearing technology, which typically integrates two radial bearings and one axial bearing to suspend the rotor, are sensitive to changes in impeller mass properties. This article focuses on modular magnetically levitated rotor technology, which enables drivelines with two or more impellers and three or more radial active magnetic bearings (AMBs). This configuration ensures the reliability and robustness of the rotordynamic behavior by providing a structure that enables adaptable integration of components, such as compressors and turbines, onto the same long high-speed shaft. The structure considered here includes a 2-MW, 12 000 r/min induction machine with three radial magnetic bearings and a rotor system where the impeller is installed on a separate shaft and connected to the motor drive with a flexible coupling. The main focus of this article is on the proof-of-concept testing and commissioning of such a technology, with particular attention given to modeling and control aspects. An $H_{\infty }$ loop-shaping approach is adopted for model-based control design, using a model that incorporates two flexible modes and adaptive notch structures to eliminate speed-synchronous components from the feedback signal. The AMB–rotor system modeling is validated through system identification routines. The experimental results demonstrate that the proposed modular technology provides improvements in rotordynamics despite the increased complexity of the system and control.

Model-based control laws play an important role in stabilizing and guaranteeing high performance of active magnetic bearing (AMB) suspended high-speed machines. In the case of rotating machines with significant gyroscopic effects, the modes are separated into forward and backward whirling modes. This often leads to a situation where a single controller with fixed parameters cannot stabilize the full operational region. Addressing the challenges arising from rotating machines with significant gyroscopic effects, the application of $$H_\infty$$ H ∞ –based linear parameter varying (LPV) control, scheduled as a function of rotational velocity, is considered in this paper. This approach is combined with an unbalance rejection strategy, where the notch parameter matrix is also updated as a function of velocity. The performance and stability of the MIMO closed-loop control are evaluated using generalized Nyquist diagrams, along with damping ratio and disk margins analysis. Such an analysis will serve as a unified framework to support the analysis as well as design and compare of LPV-based closed loop controllers. Validation of the proposed control approach is verified with experimental electrical machine equipped with AMBs.