Integrated vehicle positioning and navigation system, apparatus and method

A computer-based method for autonomously navigating a vehicle along a predetermined path, the method comprising the steps of:

• (1) determining a location of the vehicle, said step of determining including the steps of
• (a) determining a first position estimate of the vehicle based on signals from a satellite-based positioning system,
• (b) receiving a second position estimate of the vehicle from a motion positioning system, and
• (c) computing a third position estimate of the vehicle from said first position estimate and said second position estimate;
• (2) causing the vehicle to track the predetermined path, said step of causing including the steps of
• (a) retrieving from a table a given posture comprising reference path curvature, maximum velocity, desired heading, and desired vehicle position coordinates of the predetermined path,
• (b) determining a reference steering angle from the reference path curvature,
• (c) determining a posture error based on said retrieved posture and said third position estimate,
• (d) determining a desired steering angle from said reference steering angle and said posture error,
• (e) using said desired steering angle to direct the vehicle toward the predetermined path,
• (f) determining a commanded speed less than said maximum velocity, and
• (g) using said commanded speed to control the speed of the vehicle;
• and
• (3) causing the vehicle to detect and avoid obstacles while tracking the predetermined path.

A computer-based system for autonomously navigating a vehicle along a predetermined path, the system comprising:

• (1) positioning means for determining a location of the vehicle, said positioning means including
• (a) a first positioning system to provide a first position estimate of the vehicle based on first signals from a satellite-based positioning system,
• (b) a motion positioning system to provide a second position estimate of the vehicle based on second signals from an inertial reference unit mounted on the vehicle and a vehicle odometer, and
• (c) a processing system adapted to compute a third position estimate of the vehicle from said first position estimate and said second position estimate;
• (2) navigation means for causing the vehicle to track the predetermined path, said navigation means including
• (a) first means for retrieving from a table a given posture comprising reference path curvature, maximum velocity, desired heading, and desired vehicle position coordinates of the predetermined path,
• (b) second means for determining a reference steering angle from the reference path curvature,
• (c) third means for determining a posture error based on said retrieved posture and said third position estimate,
• (d) fourth means for determining a desired steering angle from said reference steering angle and said posture error,
• (e) fifth means for using said desired steering angle to direct the vehicle toward the predetermined path,
• (f) sixth means for determining a commanded speed less than said maximum velocity, and
• (g) seventh means for using said commanded speed to control the speed of the vehicle;
• and
• (3) detection means for causing the vehicle to detect and avoid obstacles while tracking the predetermined path.

A computer-based method for autonomously navigating a vehicle along a predetermined path, the method comprising the steps of:

• (1) determining a location of the vehicle, said step of determining including the steps of
• (a) determining a first position estimate of the vehicle based on signals from a satellite-based positioning system,
• (b) receiving a second position estimate of the vehicle from a motion positioning system based on second signals from an inertial reference unit mounted on the vehicle and a vehicle odometer, and
• (c) computing a third position estimate of the vehicle from said first position estimate and said second position estimate;
• (2) causing the vehicle to track the predetermined path, said step of causing including the steps of
• (a) retrieving from a table a given posture comprising reference path curvature, maximum velocity, desired heading, and desired vehicle position coordinates of the predetermined path,
• (b) determining a reference steering angle from the reference path curvature,
• (c) determining a posture error based on said retrieved posture and said third position estimate,
• (d) determining a desired steering angle from said reference steering angle and said posture error,
• (e) using said desired steering angle to direct the vehicle toward the predetermined path,
• (f) determining a commanded speed less than said maximum velocity, and
• (g) using said commanded speed to control the speed of the vehicle;
• and
• (3) causing the vehicle to detect and avoid obstacles while tracking the predetermined path.