Heading - The direction in which the machine is moving.
Pitch - The forward and aft grade (or mainfall) of the machine.
Orientation - The direction that the blade is facing.
Cross slope - The cross fall of the blade, orthogonal to the direction of travel.
The GPS receivers accurately calculate the positions of the GPS antennas by utilizing GPS signals and correction signals from the base station. However, the position of the cutting edge at the blade tips are the position that the AccuGrade System requires to make cut or fill information.
The Display calculates the position of the cutting edge by utilizing the machine dimensions and the GPS antenna positions. The position of the blade tips are then compared to the design in order to calculate cut and fill information.
The heading is the direction that the machine is traveling, shown in degrees, clockwise from grid north. 0 degrees equals North, 180 degrees equals South. The heading is calculated by comparing the left GPS antenna with the right GPS antenna.
Guidance for a single antenna system is not given when the machine has just been started or when the machine has lost the GPS signal.
The message "Low Accuracy (Move)" flashes on the Display (only if the Mainfall Sensor is not seen). Otherwise the "Low Accuracy GPS" message will be shown on the Display.
In this situation, wait until you are receiving high accuracy GPS signals again, move in a straight line, or do both.
Pitch is the forward / aft angle of the machine, calculated in degrees from the horizontal (0 degrees). Pitch is expressed in percentage or Rise:Run depending on the unit settings. The pitch is considered positive when the angle is above the horizontal (up at the front). The pitch is considered negative when the angle is below the horizontal (down at the front).
The pitch is calculated with the information from the GPS antenna. The AccuGrade System uses the pitch of the machine body in order to calculate the blade pitch. In Manual mode, the blade can be at any pitch and correct blade tip positions are calculated. In Auto mode the blade must be in the as-measured pitch. The pitch is derived from the design surface. If there is not enough information to calculate the pitch of the machine, the angle from the horizontal in which to apply the "antenna to blade" offsets is also unknown. Thus, unless the machine is sitting on a level surface, the blade tip coordinates are wrong.
The pitch may become inaccurate if one of the following occurs:
- The system is Started up
- The system is reporting low accuracy GPS
- The machine turns sharply
- The machine changes pitch drastically over a short distance
The message "Low Accuracy (Move)" flashes on the Display.
With an AccuGrade System and controls enabled, this occurs when an angle sensor is not connected. The message Low Accuracy (Pitch) flashes on the Display. In this situation, make sure that the pitch sensor is connected to the CAN bus. The flashing message disappears.
Orientation is the direction in which the blade is facing. The orientation is calculated from the vector between the two antennas.
Cross slope is the cross fall of the blade, orthogonal to the direction of travel (machine heading). This is significant when the machine has a blade that can be angled with respect to the body of the machine. Positive cross slope rises to the right. With respect to the left blade tip, the cross slope is considered positive when the right blade tip is high, and negative when the right blade tip is low.