Title page for ETD etd-12142009-000547

Type of Document Master's Thesis
Author Hopkins, Brad Michael
URN etd-12142009-000547
Title Adaptive Rollover Control Algorithm Based on an Off-Road Tire Model
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Taheri, Saied Committee Chair
Ahmadian, Mehdi Committee Member
Southward, Steve C. Committee Member
  • vehicle handling stability
  • scaling factors
  • adaptive control
  • Pacejka Magic Formula
  • off-road tire model
Date of Defense 2009-11-30
Availability unrestricted
Adaptive Rollover Control Algorithm Based on an Off-Road Tire Model

Brad Michael Hopkins


Due to a recent number of undesired rollovers in the field for the studied vehicle, rollover

mitigation strategies have been investigated and developed. This research begins with the study

of the tire, as it is the single component on the vehicle responsible for generating all of the non-inertial

forces to direct the motion of the vehicle. Tire force and moment behavior has been

researched extensively and several accurate tire models exist. However, not much research has

been performed on off-road tire models. This research develops an off-road tire model for the

studied vehicle by first using data from rolling road testing to develop a Pacejka Magic Formula

tire model and then extending it to off-road surfaces through the use of scaling factors. The

scaling factors are multipliers in the Magic Formula that describe how different aspects of the

force and moment curves scale when the tire is driven on different surfaces. Scaling factors for

dirt and gravel driving surfaces were obtained by using an existing portable tire test rig to

perform force and moment tests on a passenger tire driven on these surfaces. The off-road tire

model was then used as a basis for developing control algorithms to prevent vehicle rollover on

off-road terrain. Specifically, a direct yaw control (DYC) algorithm based on Lyapunov direct

method and an emergency roll control (ERC) algorithm based on a rollover coefficient were

developed. Emergency evasive maneuvers were performed in a simulation environment on the

studied vehicle driven on dry asphalt, dirt, and gravel for the controlled and uncontrolled cases.

Results show that the proposed control algorithms significantly improve vehicle stability and

prevent rollover on a variety of driving surfaces.

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