Fu-Cheng Wang

PERFORMANCE BENEFITS IN PASSIVE VEHICLE SUSPENSIONS EMPLOYING INERTERS

A new ideal mechanical one-port network element named the inerter was recently introduced, and shown to be realisable, with the property that the applied force is proportional to the relative acceleration across the element. This paper makes a comparative study of several simple passive suspension struts, each containing at most one damper and inerter as a preliminary investigation into the potential performance advantages of the element. Improved performance for several different measures in a quarter-car model is demonstrated here in comparison with a conventional passive suspension strut. A study of a full-car model is also undertaken where performance improvements are also shown in comparison to conventional passive suspension struts. A prototype inerter has been built and tested. Experimental results are presented which demonstrate a characteristic phase advance property which cannot be achieved with conventional passive struts consisting of springs and dampers only.

Controller parameterization for disturbance response decoupling: application to vehicle active suspension control

This paper derives a parameterization of the set of all stabilizing controllers for a given plant which leaves some prespecified closed-loop transfer function fixed. This result is motivated by the need to independently shape several different disturbance transmission paths in vehicle active suspension control. The result is studied in the context of quarter-, half-, and full-car vehicle models, to derive appropriate controller structures. A controller design is carried out for the full-car case and simulated with a nonlinear vehicle dynamics model.

The Performance Improvements of Train Suspension Systems with Mechanical Networks Employing Inerters

This paper investigates the performance benefits of train suspension systems employing a new mechanical network element called an inerter. An inerter is a true mechanical two-terminal element with the applied force proportional to the relative acceleration across the terminals. Until now, ideal inerters have been applied to car and motorcycle suspension systems, for which a significant performance improvement was reported. In this paper, we discuss the performance benefits of train suspension systems employing inerters. The study was carried out in three phases. First, fixed suspension structures were applied to train suspension systems, and optimised for two performance measures. Secondly, this optimisation was further carried out using linear matrix inequality approaches to discuss the achievable performance of passive networks. The resulting networks can then be realised by synthesis methods, such as the Brune and Bott–Duffin realisation. Finally, the nonlinear properties of inerter models and their impact on system performance were discussed. From the results, the inerter was deemed effective in improving the performance of train suspension systems.

Impact of inerter nonlinearities on vehicle suspension control

This paper discusses the nonlinear properties of inerters and their impact on vehicle suspension control. The inerter was recently introduced as an ideal mechanical two-terminal element, which is a substitute for the mass element, where the applied force is proportional to the relative acceleration across the terminals. Until now, ideal inerters have been applied to vehicle, motorcycle and train suspension systems, in which significant performance improvement was achieved. However, due to the mechanical construction, some nonlinear properties of the existing mechanical models of inerters are noted. This paper investigates the inerter nonlinearities, including friction, backlash and the elastic effect, and their influence on vehicle suspension performance. A testing platform is also built to verify the nonlinear properties of the inerter model.

The lateral stability of train suspension systems employing inerters

This paper investigates the benefits of lateral stability of train suspension systems employing a newly developed mechanical network element known as an inerter. An inerter was proposed as an ideal mechanical two-port element to substitute for the mass element in the mechanical/electrical analogy. As of now, inerters have been successfully applied to car and motorcycle suspension systems, for which significant performance benefits were reported. This paper discusses the improvements on lateral stability of train suspension systems employing inerters. The study was carried out in three parts. First, an existing 12 degrees-of-freedom (DOF) train model was built and verified by a multi-body-builder, AutoSimTM. Second, inerters were applied to the train suspension system to increase the critical speed. Finally, the discussion was extended to a 16-DOF model to demonstrate the performance improvement by inerters. From the results, inerters were deemed effective in improving the lateral stability of train suspension systems.

Vehicle suspensions with a mechatronic network strut

This paper applies a novel mechatronic network strut to vehicle suspensions and discusses the benefits of system performance. The proposed mechatronic strut consists of a ball-screw inerter and permanent magnet electric machinery, such that the system impedance can be realised through a combination of mechanical and electrical networks. Applying the mechatronic strut to vehicle suspensions, we evaluate the improvement of system performance using passive electrical networks. Furthermore, a prototype mechatronic strut is constructed for properties verification. Finally, nonlinearities of the mechatronic strut are taken into account to modify the suspension design. From the simulation and experimental results, the proposed mechatronic network strut is shown to be effective.

Stability and performance analysis of a full-train system with inerters

This paper discusses the use of inerters to improve the stability and performance of a full-train system. First, we construct a 28 degree-of-freedom train model in AutoSim, and obtain a linearised model for analysis in Matlab. Then, the benefits of inerters are investigated by the critical speed, settling time and passenger comfort. In addition, we apply a new mechatronic network for further performance improvement, and synthesise the optimal electrical circuit for experimental verification. From the results, inerters are shown to be effective in improving the stability and performance of train systems.

The Performance Improvements of Train Suspension Systems with Inerters

This paper investigates the performance benefits of train suspension systems employing a new mechanical network element, called inerter. Combined with traditional passive suspension elements - dampers and springs, inerter is shown to be capable of improving the performance, in terms of the passenger comfort, system dynamics and stability (safety), of the train suspension systems. Furthermore, a motor-driven platform is constructed to test the properties of suspension struts with inerters

Mechatronic suspension design and its applications to vehicle suspension control

This paper proposes the design of a novel mechatronic suspension strut, and investigates the performance benefits of vehicle suspension systems employing it. The proposed mechatronic suspension strut consists of a ball-screw inerter and permanent magnet electric machinery (PMEM), such that the system impedance can be realized through the combination of mechanical and electrical networks. Furthermore, we apply the mechatronic strut to vehicle suspension control, and discuss performance improvement. From the results, the proposed mechatronic suspension is deemed effective.

Disturbance response decoupling and achievable performance with application to vehicle active suspension.

This paper derives a structural condition on the controller for a given (stable) plant which guarantees that some prespecified closed-loop transfer function is the same as in the open loop. We also present conditions to test whether the achievable dynamic response of other transmission paths remains effectively the same if the controller is so restricted. The results are applied to simple quarter- and half-car vehicle models, and illustrated numerically for a double-wishbone halfcar model.