John M. Starkey

Effects of Model Complexity on the Performance of Automated Vehicle Steering Controllers: Model Development, Validation and Comparison

SUMMARY Recent research on autonomous highway vehicles has begun to focus on lateral control strategies. The initial work has focused on vehicle control during low-g maneuvers at constant vehicle speed, typical of lane merging and normal highway driving. In this paper, and its companion paper, to follow, the lateral control of vehicles during high-g emergency maneuvers is addressed. Models of the vehicle dynamics are developed, showing the accuracy of the different models under low and high-g conditions. Specifically, body roll, tire and drive-train dynamics, tire force saturation, and tire side force lag are shown to be important effects to include in models for emergency maneuvers. Current controllers, designed for low-g maneuvers only, neglect these effects. The follow on paper demonstrates the performance of lateral controllers during high-g lateral emergency maneuvers using these vehicle models.

ENGINE MOUNT OPTIMIZATION

Recent work in design optimization has led to software which allows the designer to indicate frequency bands which are undesirable. The software determines the optimal amount of several design alterations which will move system natural frequencies from undesirable bands. This design procedure is shown to be effective in selecting stiffness, orientation, and location of engine mounts which remove engine natural frequencies from the range excited at idle.

Effects of Model Complexity on the Performance of Automated Vehicle Steering Controllers: Controller Development and Evaluation

SUMMARY Due to increased traffic congestion and travel times, research in Advanced Vehicle Control Systems (AVCS) has focused on automated lateral and headway control. Automated vehicles are seen as a way to increase freeway capacity and vehicle speeds while reducing accidents due to human error. Recent research in automated lateral control has focused on vehicle control during low-g maneuvers. To increase safety, automated lateral controllers will need to recognize and react to emergency situations. This paper investigates the effects of vehicle and tire model order on the response of automated vehicles to an emergency step lane change using a controller based on linear vehicle and tire models. From these studies it is concluded that control strategies based solely on linear vehicle and tire models are inadequate for emergency vehicle maneuvers. A strategy is then proposed to automatically control vehicles through emergency maneuvers. Here the response of a nonlinear vehicle model is used with a linear s...

An Experimentally Validated Physical Model of a High-Performance Mono-Tube Damper

A mathematical model of a gas-charged mono-tube racing damper is presented. The model includes bleed orifice, piston leakage, and shim stack flows. It also includes models of the floating piston and the stiffness characteristics of the shim stacks. The model is validated with experimental tests on an Ohlins WCJ 22/6 damper and shown to be accurate. The model is exercised to show the effects of tuning on damper performance. The important results of the exercise are 1) the pressure variation on the compression side of the piston is insignificant relative to that on the rebound side because of the gas charge, 2) valve shim stiffness can be successfully modeled using stacked thin circular plates, 3) bleed orifice settings dominate the low speed regime, and 4) shim stack stiffness dominates the high speed regime.

Nonlinear-gain-optimized controller development and evaluation for automated emergency vehicle steering

Earlier research in advanced vehicle control systems (AVCS) has focused on automated lateral and headway control during low-g maneuvers. However, most emergency situations involve high-g maneuvers where vehicle performance becomes nonlinear. Robust controllers need to be developed that can react to these emergency situations. This paper investigates the development of a nonlinear-gain-optimized (NGO) controller for automated lateral control during emergencies. The strategy is to use a linear model to define the state model and a nonlinear model to optimize the feedback gains for high-g emergency maneuvers. The performance of the NGO controller is presented at 15 and 30 m/s for a step lane change and a double lane change. The NGO controllers robustness is investigated with respect to changes in tire parameters and the number of passengers.

A Web-Based Online Collaboration Tool for Formulating Senior Design Projects

A well formed senior design project is known to have significant benefits in terms of project outcome, student motivation, team cohesiveness, engagement, and student learning. Defining a good problem statement, forming a team of compatible and appropriately skilled students, and selecting an appropriate faculty mentor are critical aspects of project formation. Therefore, students in Mechanical Engineering at Purdue University are encouraged to suggest project ideas, form teams, and have them approved by the course coordinator before the semester starts. While there is significant literature on senior design projects, most of the existing work is focused on activities after the problem is defined and the teams are formed. There is a lack of mechanisms and tools to guide the project formation phase in senior design projects, which makes it challenging for students and faculty to collaboratively develop and refine project ideas and to establish appropriate teams. To address this challenge, we have implemented an online collaboration tool to share, discuss and obtain feedback on project ideas, and to facilitate collaboration among students and faculty prior to the start of the semester. Through an online survey and questionnaire to students, we are exploring the impact of the collaboration tool on the senior design project formation process. In this paper we present the design of the tool and the results from our ongoing study in the senior design class at Purdue Mechanical Engineering.Copyright