System and method for autonomously steering a vehicle

A software product stored in non-transitory memory having instructions which, when executed by a processor, causes the processor to:

• receive vehicle sensed data relating to the operation of the vehicle, the vehicle sensed data including a sensed velocity of the vehicle;
• identify a first lane marker and a second lane marker of the roadway based upon the sensed data;
• determine a reference path for the vehicle based at least in part upon the first and second lane markers;
• calculating a feed-forward control output based at least in part upon a curvature of the first lane marker and a curvature of the second lane marker;
• calculate a lateral position of the vehicle relative to the reference path based at least partly upon the vehicle sensed data, and a lateral position error based upon the lateral position;
• calculate a heading angle of the vehicle relative to the reference path based at least partly upon the vehicle sensed data, and a heading angle error based at least partly upon the heading angle;
• calculate a feedback control output using a nonlinear control function which is based at least partly upon the lateral position error, the heading angle error, and the sensed velocity of the vehicle;
• generate a vehicle steering control output based upon the feed-forward control output and the feedback control output, the vehicle control output for steering the vehicle;
• and
• autonomously steer the vehicle based at least partly upon the vehicle steering control output.

A system for controlling the steering of a vehicle along a roadway, comprising:

• one or more first sensors sensing objects within a field of view of the vehicle, including a first lane marker and a second lane marker of the roadway;
• one or more second sensors sensing an operation of the vehicle along the roadway;
• and
• a controller coupled to the one or more first sensors and the one or more second sensors, the controller including instructions which, when executed, cause the controller to:
• identify a first lane marker and a second lane marker of the roadway based upon the sensed data;
• determine a reference path for the vehicle based at least in part upon the first and second lane markers;
• calculate a feed-forward control output based at least in part upon a curvature of the first lane marker and a curvature of the second lane marker;
• calculate a lateral position of the vehicle relative to the reference path based at least partly upon the vehicle sensed data, and a lateral position error based upon the lateral position;
• calculate a heading angle of the vehicle relative to the reference path based at least partly upon the vehicle sensed data, and a heading angle error based at least partly upon the heading angle;
• calculate a feedback control output using a nonlinear control function which is based at least partly upon the lateral position error, the heading angle error, and the sensed velocity of the vehicle;
• generate a vehicle steering control output based upon the feed-forward control output and the feedback control output, the vehicle control output for steering the vehicle;
• and
• autonomously steer the vehicle based at least partly upon the vehicle steering control output.