This study is part of a cooperation between BMW AG and Technische Universitat Munchen, in order to design a road simulator for Squeak and Rattle studies based on electromagnetic actuators.
The study covers the field of decoupling control and adaptive inverse control, applied to a multi-post road simulator with electromagnetic actuators. The objective is to derive a controller which is robust and stabilizes the system without disturbances, thereto it is important to strive for a suitable bandwidth.
At first the different control theory areas are covered and divided into the main problem groups, stabilization through state-feedback and bandwidth-adjustment measures through feedforward-filters. This is followed by the system modelling, where an actuator model is designed, with separate modelling steps for the electric, magnetic and mechanical parts. A rigid body vehicle model is derived and connected to four actuators. This leads to the complete system model, which is balanced and analyzed in terms of stability, controllabilityand observability.
The model is a prerequisite for the design of the controller. Next the control theory presented is applied to the derived model in terms of a decoupling controller and a reduced observer to stabilize the system. The stabilized system is attenuated with adaptive multi input multi output invserse control concepts, as well as static feedforward-filters. The finished control structure is simulated for a two actuator and a four actuator rig. Furthermore, tests are made on an actual two-post road simulator with electromagnetic actuators, verifying the simulations.
The objectives stated in the project are achieved on the actual test rig, and proved to be robust enough for the purposes of this and future experiments. The design goals for the rig in the scope of this study were achieved with a combination of state-space decoupling controller, reduced observer, tracking error estimator and time waveform replication.
Author: Sundqvist, Niclas