Abstract: A mobile ground vehicle is provided intended to move along a path oriented in predetermined position relative to the vehicle and blower structure is mounted on the vehicle and includes an outlet opening outwardly from the vehicle laterally of the aforementioned path. Deflector structure is operatively associated with the outlet for variably deflecting the discharge of air from the outlet through an arch of angular deflection disposed in a plane generally paralleling the aforementioned path and including extremes inclined in opposite directions along the path. Drive structure is operatively associated with the deflector structure for driving the latter between the extremes of angular deflection thereof and object sensor structure is carried by the vehicle for sensing objects past which the vehicle is moved.