For decades, the pavement engineering community has continued to drive improvements in accuracy and repeatability of terrain measurement systems. Traditional terrain measurement systems are tailored for a measuring a specific scale and resolution and hence application scope. These systems tend to focus on surface roughness alone and reject either fine macrotexture or large-scale global features. This work proposes a novel improvement to the terrain measurement system, by increasing the capability to measure the terrain surface at a variety of scales. By increasing the scales of measurement, desired aspects of the terrain profile can be accurately obtained for a wide variety of applications without having to omit large-scale features or macrotexture. In addition to increasing the capabilities of the traditional terrain measurement system, methods for addressing and minimizing sources of error within the system are developed. Major sources of error in terrain measurement systems, which compromise the accuracy and repeatability of the resulting measured terrain, include scanning laser uncertainty, inertial navigation system (INS) uncertainty and drift, triggering and time synchronization, system misalignment, and post-processing errors. These errors are addressed, and an improved Vehicle Terrain Measurement System (VTMS) is proposed. A triggering and time synchronization system is developed and insight into the development of this system for a terrain measurement system is gained. All three scanning lasers are individually assessed for linearity, with sample profiles analyzed for agreement. The improved VTMS represents a significant development in terrain measurement systems. / Master of Science

The emergence of high-fidelity vehicle and tire models has raised the requirements for terrain measurement capabilities. Inaccuracies that were once tolerable for measurement of general terrain roughness are no longer acceptable for these new applications. The techniques in this work seek to improve the quality of terrain measurement in addition to providing an objective way to describe the accuracy of these measurements. The first portion of this work develops an accuracy verification procedure for terrain measurement systems. This procedure involves a static test to assess the limitations of the profiler's laser height sensor, and a corresponding dynamic test to evaluate the limitations of the positioning sensors. Even with a well calibrated system, inertial errors will accumulate. The second portion of this work develops techniques to address these inertial errors in the data post-processing phase. A general correction technique is developed for any terrain type and a more computationally efficient technique is developed for smooth surfaces. For basic ride and handling simulations, 3D terrain surfaces are computationally impractical, as the models used for these simulations only require point excitation. Current road profilers acquiring these 2D data use single-point lasers that capture localized disturbances that would be mechanically filtered by the tire and suspension in the physical vehicle system. The final chapter in this work develops a method to extract a 2D terrain profile from a 3D terrain surface. By considering all of the information in the tire contact patch, the filtering properties of the tire are approximately emulated. / Master of Science