Speed control for motor vehicles

A trailer backup assist system, comprising:

• a hitch angle sensor configured to determine a hitch angle between a vehicle and a trailer attached thereto;
• an input device configured to accept an input command corresponding to a trailer path command curvature;
• and
• a controller configured to determine a vehicle threshold speed limit by determining a first vehicle speed limit based on the hitch angle and a second vehicle speed limit based on the command curvature, wherein the controller generates a command to limit vehicle speed in a reverse direction below the threshold speed limit and the vehicle threshold speed limit is set to the higher of the first and second vehicle speed limits when a magnitude of an input command is decreasing and the vehicle threshold speed limit is set to the lower of the first and second vehicle speed limits when a magnitude of input command is increasing.