Hydraulic system having dual tilt blade control

A hydraulic system for a machine, comprising:

• a tank configured to hold a supply of fluid;
• a pump configured to draw fluid from the tank and pressurize the fluid;
• a first cylinder operatively connected between a first side of a work tool and a first undercarriage assembly of the machine;
• a second cylinder operatively connected between a second side of the work tool and a second undercarriage assembly of the machine;
• a first electro-hydraulic valve associated with the first cylinder and configured to selectively regulate a flow of pressurized fluid to the first cylinder independently of the second cylinder;
• a second electro-hydraulic valve associated with the second cylinder and configured to selectively regulate a flow of pressurized fluid to the second cylinder independently of the first cylinder;
• an operator interface device configured to generate signals that are indicative of desired work tool movement when manipulated by an operator, and
• a controller in communication with each of the first and second electro-hydraulic valves and the operator interface device, the controller being configured to:
• selectively generate valve position commands directed to the first and second electro-hydraulic valves that result in a single-action left tilt, a dual-action left tilt, a single-action right tilt, a dual-action right tilt, a pitch, and a combination tilt/pitch of the work tool;
• receive a first signal indicative of a desired tilting of the work tool and a second signal indicative of a desired pitching of the work tool;
• generate combined valve position commands directed to the first and second electro-hydraulic valves that are functions of the first and second signals;
• normalize the first and second signals and sum normalized values of the first and second signals to determine the combined valve position commands;
• reference sums of the normalized values with a relationship map stored in memory to determine the combined valve position commands;
• reduce the valve position commands by an amount when the first and second signals are received separately;
• and
• reduce the combined valve position commands by a lower amount when the first and second signals are received simultaneously.