On a dozer, a semi-automatic system automatically translates a joystick to control blade elevation and provides an indicator display to guide manual control of blade slope angle. A mechanical linkage operably couples the joystick to an electrical motor. A computational system receives measurements from measurement units mounted on the dozer; calculates estimated values of elevation and slope angle; compares the estimated values to reference values; and calculates error and control signals. Drivers generate a motor drive signal and a display drive signal. In response to the motor drive signal, the electrical motor translates the joystick to control elevation. In response to the display drive signal, the indicator display generates a graphical representation of the status of slope angle. When the operator needs to take manual control, a proximity sensor detects the presence of at least a portion of the operator's hand, wrist, or forearm and disengages automatic control of elevation.