Grass mower

A grass mower comprising:

• a drive wheel unit;
• a variable speed drive mechanism for driving the drive wheel unit;
• a mower unit having a cutter blade;
• a cutter blade drive mechanism for rotatably driving the mower unit;
• a man-operable vehicle speed controlling tool which is operated in a range from a zero vehicle speed position to a maximal vehicle speed position;
• an operation detection section for detecting an operational position of the man-operable vehicle speed controlling tool;
• a vehicle speed instruction value calculation section for generating a vehicle speed instruction value including a maximal vehicle speed, based on the operational position of the man-operable vehicle speed controlling tool detected by the operation detection section;
• a mode selection section for selecting a control mode from a plurality of control modes;
• a control table in which a plurality of control parameters are set, the control parameters being provided for the respective control modes, each of the control parameters including a rotational speed value of the cutter blade and a maximal vehicle speed value corresponding to the rotational speed value;
• a vehicle speed control target value calculation section configured to calculate a vehicle speed control target value, based on a vehicle speed instruction value generated by the vehicle speed instruction value calculation section and a selected control parameter corresponding to the control mode selected by the mode selection section;
• a traveling control section configured to control the variable speed drive mechanism based on the vehicle speed control target value;
• a cutter blade control target value calculation section configured to calculate a rotational speed control target value for the cutter blade, based on the selected control parameter;
• and
• a cutter blade control section configured to control the cutter blade drive mechanism based on the rotational speed control target value.