Automatic control device for an earth working equipment

An automatic control device for earth working equipment and a blade for said earth working equipment, said control device comprising:

• blade control means for controlling lifting and lowering of the blade in accordance with a difference between the present height and a preset height of the blade;
• tilt angle control means for controlling a tilt angle of the blade in accordance with a difference between the present tilt angle and a preset tilt angle, said tilt angle control means including an inclinometer coupled directly to the blade to detect the tilt angle of the blade;
• and
• blade preference means for inhibiting an operation of said tilt angle control means while the blade is being lifted or lowered and enabling the operation of said tilt angle control means while the blade is not being lifted or lowered.

An automatic control system for use in earth working equipment of the type which includes a body, a movable frame coupled to the body and a blade carried on the frame, said control system comprising:

• inclinometer means for providing at least one inclination signal corresponding to the inclination of the body, wherein said at least one inclination signal includes an unwanted acceleration component caused by movement of the body;
• an acceleration compensation arithmetic circuit connected to the inclinometer means for substantially removing said acceleration component to thereby provide an output signal which is substantially a function of body inclination alone;
• detection means for providing an output corresponding to the angle of the frame with respect to the body;
• an inclination arithmetic circuit for receiving the outputs of the acceleration compensation circuit and the detection means and for calculating a present inclination angle of the frame with respect to the ground;
• and
• blade control means for controlling the position of the blade in response to the difference between the present inclination angle and a reference value.