Retractable line guidance for self-propelled machines

Retractable line guidance for a self-propelled machine (100,200), such as a self-propelled lawn mower, is provided by an operator (102,202) moving a string or line to control the speed and direction of movement of the machine (104,204). A retractable and extendable line (224) is mounted on the machine (204) and is under tension in a retraction direction when the line is extended. A length of extension of the line is monitored, and a speed of movement of the machine is controlled in response to the length of extension of the line to maintain the length of extension of the line at a selected length. An angle of the line with respect to the machine is monitored, and a direction of movement of the machine is controlled in response to the angle of the line to maintain the angle of the line at a selected angle.