AccuGrade GPS System Caterpillar

AccuGrade Overview

Angle Sensor on the Blade

The angle sensor is mounted on the blade. Along with the GPS components, the angle sensor helps to determine the position of the blade, as well as the forward/aft pitch of the blade.

Valve Control Module and Valves on the Machine

The A4:M1 valve controller uses the cut/fill values in order to drive the control valves. The blade control valves move the blade so that the blade works to design.

The A4:M1 control module processes information from the CD550A display. The A4:M1 sends information to the hydraulic valves to move the blade automatically.

Blade Control Lever Switches on the Machine

Illustration 1	g01065925
Joystick Control Switch (A) Trigger Switch (B) Decrement/Auto Button (C) Increment/Manual Button

The blade control lever incorporates two push button switches and a trigger switch. The functions of the push button switches change, depending on the state of the trigger switch. Table 1 describes the functions of the push button switches, relative to the state of the trigger switch.

Note: In the remainder of this section, the push button switches on the blade control lever will be referred to by their function. For example, "Push the Auto button" means "Push the left button, with the trigger switch out".

Start-Up Automatic Control Checks

The "AccuGrade GPS" software checks which devices are present, and the current firmware version number of each device. When automatic controls have been enabled during machine configuration, the system checks for responses from the AS400 angle sensor, the A4:M1 control module, and the MS980C GPS receivers.

If any device does not respond, the following message appears: "Some of the required system devices are not responding. Press the OK key in order to diagnose".

When you press the OK key, the Diagnostics dialog appears. Refer to Illustration 2.

Illustration 2	g01122099

The Diagnostics dialog displays a list of devices configured for the automatic controls system.

Note: Only devices that are required for the current configuration are listed. Additional devices may be present but if the devices are not currently required, the devices are not listed.

The Diagnostics dialog lists each device and reports the following:

• A device name

• The status

• The application firmware version number

• The loader firmware version

The application firmware must be the correct version to activate the automatic controls.

In order to check the system again, press the "Recheck" soft key. The status list is updated to show any changes that are detected.

Application Firmware Version

The application firmware version number indicates which devices are detected and which devices have the correct version of the firmware loaded.

Note: When version numbers are displayed for all devices in the list, you can use automatic controls.

Old Firmware

If either the firmware or the loader is too old, the device is detected, but you cannot use automatic controls until the device firmware is updated. The Status column displays the minimum firmware required.

Not found

If the message "Not found" appears beside a device, the device was not detected.

You cannot use automatic controls if a device is not found.

Configuration Failed

If the configuration file sent to the GPS receiver failed, try loading a design surface to send another configuration file.

If the configuration file sent to the sensors failed, press the "Recheck" soft key in order to send another configuration file to the sensors.

GPS

In order to view detailed diagnostics about the GPS receiver and data radio link, press the "GPS" soft key.

Automatic Control States

Automatic controls can be in one of the following states:

• Manual

• Auto

• Inactive-Auto

• Unknown

The automatic control status indicator appears in the lower left of the screen when the automatic control option is set. This indicator shows what state the automatic controls are in.

Note: If the automatic controls state is not displayed in the Plan View, the Cross-section View, the Profile View, or the Text Views and the valve speed dialogs, then the automatic controls are not enabled in the Setup Menu or a required device is not responding.

Manual

When the Manual button (right button/trigger out) is pressed, the automatic controls are deactivated. Horizontal and vertical guidance are still provided through the CD550A display and light bars.

The Plan View in Illustration 3 shows the AccuGrade GPS system in Manual state.

Illustration 3	g01109176
AccuGrade system in Manual state

Auto

When the Auto button (left button/trigger out) is pressed, and the status indicator shows Auto in green, the automatic controls are activated and are in use.

In Auto state, the AccuGrade GPS system controls the lift and the tilt movements of the blade.

Note: If Auto flashes in red on the status indicator, the AccuGrade GPS auto system is in the Inactive-Auto state. Automatic controls are disabled.

The Cross-section View in Illustration 4 shows the AccuGrade system in Auto state.

Illustration 4	g01109177
AccuGrade GPS system in Auto state

Automatic controls will stop operating when the cut and fill value for either blade tip exceeds 0.2 m (8 inches). Automatic control of the blade resumes when the blade tips are both within 0.2 m of the working surface.

Inactive-Auto

When the Auto button (left button/trigger out) is pressed, and Auto flashes in red on the status indicator, the automatic controls are set to Inactive-Auto state.

In Inactive-Auto state, the automatic controls of the AccuGrade GPS system are disabled. Horizontal and vertical guidance are still provided through the CD550A display and light bars. Inactive-Auto state indicates that the operator has attempted to activate the automatic controls, but the system is not able to drive the automatic controls.

Controls enter the Inactive-Auto state if any of the following situations occur:

Note: When turned on, the beeper will sound for these conditions.

• A device can no longer be detected.

• The automatic valves have not been driven (the valves have been inactive) for 60 seconds or longer.

• CD550A display starts (when the Auto/Manual switch is set to Auto).

• No design is loaded.

• Designs are changed.

• The machine is off the design for more than 60 seconds.

• You access the Alignment, Horizontal Offset or Elevation Offset dialogs.

• You access the "Setup Menu - Configuration", including automatic entry into the Diagnostics dialog.

• Any required AccuGrade GPS component stops working.

• You receive low accuracy GPS positions.

• The CD550A display shuts down.

• The park brake is on.

• The implement lock-out switch is on.

• The valves have not been calibrated.

In order to change from Inactive-Auto state to Auto complete the following steps:

1. Correct any safety condition or start-up errors such as:
   • The park brake is on.

   • The implement lock-out switch is on.

2. Press the Auto button (left button/trigger out).

In order to change the automatic control state to Manual, press the Manual button (right button/trigger out) at any time.

Unknown

When the CD550A display receives no information about the state of the automatic controls, the automatic controls change to the Unknown state. When this occurs, check the A4:M1 control module.

Using Automatic Controls

Before you can use automatic controls, make sure that you complete the following actions:

• Configure the automatic controls.

• Complete the start-up checks. For more information, refer to the Light Bar Section.

• Pass the safety checks.

• Turn off the implement lock-out switch.

• Turn off the parking brake.

• Press the Auto button (right button/trigger out).

Caterpillar recommends that you remain in Manual state until the following conditions are met:

• All start-up checks are done.

• You are on design.

• You are ready to start using automatic controls.

A typical sequence of actions to prepare AccuGrade GPS for a job using automatic controls is outlined in the following steps:

1. Create a working surface for vertical guidance using one of the methods in the Vertical Guidance Section.

2. Select an alignment for horizontal guidance using one of the methods in the Horizontal Guidance Section.

3. With the automatic controls in Manual state, line up the machine for the pass and move the blade so that the blade will cut or fill a reasonable amount of material. Set the vertical offset ("V. Offset: <Value>") so that the cut/fill indicator on the light bars reads approximately 0 (zero).

4. Start to move smoothly along the pass.

Show/hide table

NOTICE
If the material surface you are working in is too hard, the blade may not penetrate the material. The front end of the machine may be lifted off of the surface.

5. Press the Auto button (left button/trigger out) in order to activate the automatic controls.

6. At the end of the pass, press the Manual button (right button/trigger out) in order to deactivate the automatic controls, and then lift the blade.

7. Repeat Step 3 through Step 6 until the vertical offset is reduced to 0 (zero) and the blade is on the working surface.

Note: If the blade is too full, use the vertical offset increment switch to reduce the amount of material being moved on the pass. You can do this at any stage.

Guidance

Any of the four auto states provide guidance information on the CD550A display and on the light bars.

When the automatic controls are active, you can use the horizontal guidance to manually steer the machine and the vertical guidance to monitor the performance of the automatic controls.

Vertical Offset Increment and Decrement Buttons

Rather than carving out large amounts of material in a single pass, Caterpillar recommends that you use vertical offsets to progressively work down to the working surface.

Use the vertical offset buttons in order to change the vertical offset by a set amount without affecting the state of the automatic controls. In order to increase the vertical offset, press the Increment button (right button/trigger in). In order to decrease the vertical offset, press the Decrement button (left button/trigger in).

Refer to Operation and Maintenance Manual, "Setting a Vertical Offset" in order to change the increment offset value.

Note: When you use the Elevation Offset dialog, you disable the automatic controls.

Customizing Automatic Controls

The AccuGrade GPS auto system has two options to optimize the automatic controls for your work site:

• The valve speed

• the vertical offset increment

Valve Speed

Use the Valve Speed dialog to change the speed of the valves that automatically control the blade. The correct valve speeds depend on the type of material that the machine is moving. You can also set the valve speeds to suit the current working conditions. For example, constructing the base grades or the finished grades.

If the valve speeds are set too high, the system reacts too quickly. This can cause the system to become unstable and the blade to overshoot and then return to grade. If the valve speeds are set too low, the system will react too slowly, and the blade will take too long to return to an on-grade position. Both situations will cause inaccuracies in the final surface.

Vertical offset increment

Note: The "Vertical offset increment" dialog is a site selectable feature. Consult your site champion in order to turn this feature ON.

If this feature is turned ON, the "Vertical Offset Increment" dialog is used in order to set the amount each press of the vertical offset buttons increases or decreases the vertical offset. Refer to Operation and Maintenance Manual, "Vertical Offset - Set" in order to modify the offset increment value.