Vehicle Dynamics & Control - 01 Coordinate systems

Introduction to Vehicle Dynamics and Control

Overview of Kinematics and Kinetics

• The lecture begins with an introduction to vehicle dynamics, focusing on the kinematic bicycle model. Background material on dynamics and control will be reviewed throughout the course.

• Kinematics refers to the geometric description of motion for point masses or rigid bodies, while kinetics (or dynamics) deals with the laws that cause motion, such as Newton's laws.

• It is crucial to distinguish between kinematics and kinetics when analyzing dynamical systems; both concepts will be explored in relation to vehicles.

Reference Frames in Vehicle Dynamics

Inertial Reference Frame

• The inertial reference frame is fixed to the Earth, where Newton's laws apply under gravitational influence. Coordinates X, Y, and Z are defined for this frame.

• In this frame:

• Z-axis points vertically in line with gravity,

• X and Y axes represent the horizontal plane perpendicular to gravity.

Vehicle Reference Frame

• The vehicle reference frame is attached to a specific point on the vehicle (e.g., center of gravity or rear axle midpoint).

• According to ISO 885 standards:

• XV points forward,

• YV points left,

• ZV points upward from the vehicle reference point.

Horizontal Frame

• The horizontal frame has its origin at the vehicle reference point but differs in orientation from the vehicle frame.

• Its coordinates (x, y, z):

• x and y are projections of XV and YV onto a horizontal plane,

• z is orthogonal to this plane.

Path Frame Definition

• The path frame follows a predetermined path defined by coordinate s. This system includes three axes:

• D-axis: Tangential direction along the path.

• E-axis: Perpendicular within a road plane defined at origin.

• N-axis: Perpendicular direction relative to the road plane forming a right-handed Cartesian system.

Importance of Understanding Reference Frames