Method and system for mitigating sway of a vehicle trailer by braking the towing vehicle during the correct phase of the sway

A method for detecting and mitigating sway of a trailer being towed by a leading vehicle, the method comprising:

• using a yaw rate sensor carried on the vehicle to provide a yaw rate signal representing a yaw rate of the vehicle;
• using a yaw angle threshold detector module operably associated with an electronic controller of the vehicle to detect when a magnitude of the yaw rate signal exceeds a preset threshold, and to provide a first output signal;
• using a yaw angle zero crossing detector module operably associated with the electronic controller to detect when the trailer sways across a vehicle centerline, and to provide a second output signal indicating that the trailer has crossed the vehicle centerline;
• causing the electronic controller to use the first and second output signals to apply a plurality of brakes of the vehicle as the trailer begins swaying toward the vehicle centerline from a location on one side or the other of the vehicle centerline;
• causing the electronic controller to use the second output signal to release the plurality of brakes before the second output signal indicates that the trailer has crossed the vehicle centerline;
• and
• causing the electronic controller to reapply and release the plurality of brakes during each one of a plurality of sway cycles of the trailer only while the trailer is detected as swaying toward the vehicle centerline.

A system for detecting and mitigating sway of a trailer being towed by a leading vehicle by a selective application with optimal timing of a plurality of brakes of the vehicle, the system comprising:

• an electronic stability control (ESC) subsystem carried on the vehicle;
• a yaw rate sensor carried on the vehicle to provide a yaw rate signal representing a yaw rate of the vehicle to the ESC subsystem;
• a threshold detector module operably associated with the ESC subsystem to detect when a magnitude of the yaw rate signal exceeds a preset threshold, and to provide a first output signal indicating that the yaw rate signal has exceeded the present threshold;
• a yaw angle zero crossing detector module operably associated with an electronic controller of the vehicle to detect when the trailer is about to sway across a vehicle centerline, and to provide a second output signal indicating that the trailer is about to cross the vehicle centerline;
• the ESC subsystem configured to:
• use the first and second output signals and to apply the brakes of the vehicle as the trailer begins swaying toward the vehicle centerline from a location farthest on one side or the other from the vehicle centerline;
• to use the second output signal to release the brakes before the second output signal indicates that the trailer has crossed the vehicle centerline;
• and to reapply the plurality of brakes during each one of a plurality of sway cycles of the trailer only while the trailer is detected as swaying toward the vehicle centerline, and to release the brakes before the trailer is detected as having reached the vehicle centerline.