Lanekeeping at the limits of handling
Abstract/Contents
- Abstract
- Approximately one-third of fatal vehicle crashes in the United States involve a collision with a fixed object in the environment as the first harmful event. Lanekeeping assistance systems, designed to help the driver avoid unintended lane departures, have the potential to directly prevent these accidents. Automakers have begun to offer such active control systems, which use either the steering or the brakes to help guide the vehicle back into the lane if it begins to veer out. These systems are intended to be used during "normal" driving, and are either limited or completely shut off in highly dynamic situations, when the tires might be sliding relative to the ground due to a limited amount of available friction. This is far from ideal since the driver arguably needs more assistance when the vehicle is operating at the limits of handling, not less. In order to improve vehicle safety beyond what is currently offered, lanekeeping assistance should be extended beyond "normal" driving scenarios. This requires guarantees that the system will operate in a stable and predictable manner even in the presence of highly saturated tire forces. Finding such guarantees is the focus of this dissertation. One particular lanekeeping system, based on the idea of a virtual potential field, is used for discussion in this dissertation. It applies a steering input to the vehicle and seeks to control a combination of the vehicle's lateral and heading errors, which are measured relative to a desired path. In order to analyze this system's stability at the limits of handling, a method for including tire saturation in the vehicle model is required. By formulating the nonlinear tire force as a scaled version of the force in the linear tire region, the impact of the friction limits on the vehicle dynamics can be analyzed independently of a particular nonlinear tire model. Then, a Lyapunov-based approach for finding regions of guaranteed stability is used to show stability up to and beyond the peak of the tire curve. In addition to analyzing the potential field lanekeeping system, a framework for designing other lanekeeping feedback controllers with guaranteed stability at the limits of handling is presented. Results from a by-wire research vehicle are also included to experimentally demonstrate stability in the presence of highly saturated tires. While the focus of this dissertation is on lanekeeping assistance systems, the methods presented could also be used to design and analyze other types of driver assistance systems and vehicle control algorithms.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2013 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Talvala, Kirstin L. R |
|---|---|
| Associated with | Stanford University, Department of Mechanical Engineering. |
| Primary advisor | Gerdes, J. Christian |
| Thesis advisor | Gerdes, J. Christian |
| Thesis advisor | Okamura, Allison |
| Thesis advisor | Tomlin, Claire J, 1969- |
| Advisor | Okamura, Allison |
| Advisor | Tomlin, Claire J, 1969- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Kirstin L. R. Talvala. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2013. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2013 by Kirstin Lynne Rock Talvala
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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