This thesis describes the modelling and control of an electromechanical brake (EMB) for a drive-by-wire vehicle. The investigation comprised two components on the development, identification and assessment of an EMB model, and the development of an improved control algorithm for an EMB. / The first component of the study began with the examination of a simplified model for an electromechanical disk brake without the positive feedback of brake self-energisation. A methodology was proposed for practical identification of the model parameters on an assembled actuator. Experiments were conducted on a prototype EMB, and for the first time the model fidelity was tested in isolation without a feedback controller acting to reject disturbances. Laboratory tests of the model fidelity were complemented with closed-loop simulations against field data from a brake-by-wire test vehicle. It was determined that the EMB model reasonably predicted the key behaviours of the brake apply, force modulations and lockup due to load-dependent stick-slip friction. The limitations of the model were then identified and extensions were considered to describe secondary effects. / The second component of the study utilised the model to develop an improved control algorithm for an EMB, particularly considering the problem of tracking a brake force command from the driver, or from another vehicle control. Existing EMB controllers were seen to have a limited effectiveness; with a suboptimal handling of actuator nonlinearity, they suffered from problems of the load dependent mechanism friction, and they could not maintain performance throughout the operational envelope. These shortcomings were overcome sequentially by the development of a friction compensation algorithm and a modified control architecture to better manage actuator nonlinearity. To address model uncertainty the modified architecture was incorporated within a robust control design, but this gave an overly conservative brake performance. In a more successful approach, the modified architecture was extended with a model predictive control to optimise the EMB performance and a method for updating the control algorithm was proposed to handle uncertainty and adapt to actuator variation. At each stage experimental tests were conducted on a prototype EMB to demonstrate performance and the incremental improvements achieved. The control improvement was found to be most pronounced for fine manoeuvres whereas large manoeuvres were typically limited by the actuator constraints. / The study outcomes regarding EMB modelling, identification and control are a significant incremental advancement on prior work, and may help to facilitate the development of improved brake-by-wire platforms, anti-lock brake systems and advanced driver assist functions.
| Identifer | oai:union.ndltd.org:ADTP/245677 |
| Creators | Line, Christopher Leonard James |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
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