The Display, the Light Bars, and the various sensors are connected electrically by a system harness that allows the system components to send data and commands between each other.
Additionally, the AccuGrade System requires one of the following types of Base Stations somewhere near the project:
- Global Positioning System (GPS)
- Global Navigation Satellite System (GNSS)
Guidance Information
Guidance is given to the operator in the following two ways:
- The Display
- The Light Bars
Display
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| Illustration 1 | g01265962 |
(1) LCD (2) Soft Key Labels (3) Soft Keys (4) Escape Key (5 ) Next Key (6) Power Key (7) "+" Key (8) Arrow Keys (9) "-" Key (10) "OK" Key (11) Menu Key (12) "Data Card Slot" | |
The Display is a computer that runs the AccuGrade software. The Display has a color LCD screen in order to display guidance information and other information. The Display has push buttons that are used to operate the AccuGrade System.
Data Card Slot
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| Illustration 2 | g01265965 |
(12) "Data Card Slot" | |
The Display has a data card slot that is used for loading and saving machine and display configuration data. The data card slot is also used for loading and saving designs.
Light Bars
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| Illustration 3 | g01176126 |
Three Light Bars are installed. Each Light Bar shows different information for your blade position:
- Two vertically-mounted Light Bars give cut/fill guidance to the blade tip on each side.
- A horizontal Light Bar gives horizontal guidance from a selected alignment to the blade tip with focus.
Remote Switches
The remote switch assemblies are a set of switches that plug into the harness so that the system controls can be placed in a more convenient location. The switches are configured to perform the following system operations:
- Switch between Auto and Manual control
- Set an elevation offset
- Set a Cross Slope offset
M-Series
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| Illustration 4 | g01298981 |
Remote Switch Located on the Left Side (9) Left "Increment/Decrement" Switch (10) Left "Auto/Manual" Button | |
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| Illustration 5 | g01298993 |
Remote Switch Located on the Right Side (11) Right "Remote Elevation Offset" Switch (12) Right "Auto/Manual" Switch (13) Side Shift "Auto/Manual" Switch (3D Systems only) | |
Auto/Manual Switches
To use the remote auto/manual switches perform the following:
Press the Auto/Manual switch in order to change the current state of automatic/manual blade movement.
For example, if the system is currently not automatically driving to grade, press the "Auto/Manual" switch to provide automatic blade movement.
Alternatively, if the blade is automatically driving to grade, press the "Auto/Manual" switch in order to stop the system from providing automatic blade movement.
Note: The Auto/Manual switches are sensor side dependent. An example of this would be if you set the Cross Slope control for the right side, the Right "Auto/Manual" Switch controls Cross Slope on the right side. If you set the Cross Slope control for the left side, the Left "Auto/Manual" Switch controls the Cross Slope on the left side.
Note: The AccuGrade system allows for automatic control of the blade's side shift. Once a horizontal alignment has been selected, press the "Auto/Manual" (13) switch in order to activate the automatic control of the blade side shift. The blade will then shift from side to side in order to keep the blade tip with focus on the horizontal alignment.
Elevation Offset
Toggle the switch on the remote switch assembly to increase or decrease the elevation offset applied to the reference elevation.
The reference elevation that is shown on the LCD of the Display changes when the remote elevation offset switch is toggled.
To configure the amount by which the remote elevation offset switch increments or decrements the reference elevation, use the Elevation Offset screen in Setup mode.
Slope Offset
Toggle the switch on the remote switch assembly to increase or decrease the slope offset applied to the reference slope percentage.
The reference slope percentage shown on the Display changes when the remote slope offset switch is toggled.
To configure the amount by which the remote slope offset switch increments or decrements the reference slope, use the Slope Offset screen in Setup mode.
Note: Offset switches are sensor side dependent. An example of this would be if you set the Cross Slope control for the right side, the right side offset switch controls Cross Slope. If you set the Cross Slope control for the left side, the left side offset switch controls Cross Slope.
H-Series
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| Illustration 6 | g01116987 |
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| Illustration 7 | g01128343 |
(15) Left "Auto/Manual" Button (16) Left "Remote Elevation Offset" Switch (17) Right "Remote Elevation Offset" Switch (18) Right "Auto/Manual" Button | |
Auto/Manual Switches
To use the remote switch assembly:
Press the Auto/Manual switch in order to change the current state of automatic/manual blade movement.
For example, if the system is currently not automatically driving to grade, press the "Auto/Manual" switch to provide automatic blade movement. The "Auto/Manual" Light Emitting Diodes on the Display change from amber to green.
Alternatively, if the blade is automatically driving to grade, press the "Auto/Manual" switch in order to stop the system from providing automatic blade movement. The "Auto/Manual" Light Emitting Diodes on the Display change from green to amber.
Note: The Auto/Manual buttons are sensor side dependent. An example of this would be if you set the Cross Slope control for the right side, the Right "Auto/Manual" Button controls Cross Slope on the right side. If you set the Cross Slope control for the left side, the Left "Auto/Manual" Button controls the Cross Slope on the left side.
Elevation Offset
Toggle the switch on the remote switch assembly to increase or decrease the elevation offset applied to the reference elevation.
The reference elevation that is shown on the LCD of the Display changes when the remote elevation offset switch is toggled.
To configure the amount by which the remote elevation offset switch increments or decrements the reference elevation, use the Elevation Offset screen in Setup mode.
Slope Offset
Toggle the switch on the remote switch assembly to increase or decrease the slope offset applied to the reference slope percentage.
The reference slope percentage shown on the Display changes when the remote slope offset switch is toggled.
To configure the amount by which the remote slope offset switch increments or decrements the reference slope, use the Slope Offset screen in Setup mode.
Note: Offset switches are sensor side dependent. An example of this would be if you set the Cross Slope control for the right side, the right side offset switch controls Cross Slope. If you set the Cross Slope control for the left side, the left side offset switch controls Cross Slope.
System Sensors
The guidance information that the system can provide depends on the type of sensors and number of sensors that are installed on the machine. AccuGrade can operate with the following types of sensors:
Cross Slope Sensors
The cross slope of the cutting edge is the slope of the blade projected in the direction of travel of the machine. The cross slope information for the AccuGrade System is generated from the measurements of three sensors operating together. The Cross Slope Sensors group consists of the following sensors:
Two angle sensors - One sensor is used to measure the blade slope. The other sensor is used to measure the mainfall (pitch) of the machine. Slope sensors must be configured into the system before the information that is provided by the slope sensors can be used for guidance.
One rotation sensor - Rotation sensors measure the rotation of the blade. A rotation sensor must be configured into the system before the information it provides can be used for guidance.
Angle Sensors
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| Illustration 8 | g01184100 |
The Angle Sensor (2, 3) is a highly accurate sensor that is capable of measuring up to 100 degree slopes.
In a Cross Slope system, one Angle Sensor (2, 3) measures the actual slope of the blade, and a second Angle Sensor (2, 3) measures the slope of the machine in the direction of travel.
Rotation Sensor
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| Illustration 9 | g01184175 |
The Rotation Sensor (4) is a device that measures the change of the angle between two pivoting members. The primary application is for measuring the rotation of the blade. That measurement is used to calculate the cross slope of the blade of a machine.
Lift Sensors
Lift sensors are used to monitor the vertical displacement of the blade from some reference, such as a string line. The blade lift sensors that are used by the AccuGrade System.
- Sonic Tracers use sound in order to measure the distance to a reference object, such as a curb or string line. A Sonic Tracer must be configured into the system before the information it provides can be used for guidance.
Sonic Tracer
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| Illustration 10 | g01295051 |
ST300 Sonic Tracer | |
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| Illustration 11 | g01308993 |
ST400 Sonic Tracer | |
The Sonic Tracer uses sound waves to determine the distance to a reference surface. References can include the following items: string line, curb and gutter. Additionally, the reference can include the previous pass. Once the device has been locked onto a reference, any change in the distance from the set point causes a correction signal to be sent to the Display (1) .
The Sonic Tracer measures the length of time that is taken by the sound waves to travel between the transducer in the Sonic Tracer and the reference surface in order to determine the elevation. Once the elevation is set, any deviations in elevation are sent to the Display (1). These corrections are then sent to the valve module. Then, the valve module sends the correction signals to the proportional control valve.
Location Sensors
The location sensors that are used by the AccuGrade System allow the AccuGrade System to determine the location of the location sensors in 3 dimensional space. Location sensors used by the AccuGrade System are the Global Positioning System (GPS) receiver and the Machine Target for the Advanced Tracking System (ATS).
GPS/GNSS Receiver
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| Illustration 12 | g01178081 |
(13) GPS/GNSS Receiver (14) Mast (15) Thumb Wheel On Quick Release Bracket | |
GPS Receivers and GNSS Receivers are able to calculate their location by using information that is broadcast from satellites that are orbiting the earth and correction signals that are sent from a base station. GPS Receivers and GNSS Receivers must be configured into the AccuGrade System before the information can be used for guidance.
Machine Target
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| Illustration 13 | g01181307 |
The ATS uses a robotic theodolite in order to track an Machine Target that is attached to the blade of the machine. The robotic theodite reports the location of the Machine Target over a wireless link. The robitic theodite must be configured into the system before the information that is provided by the robotic theodite can be used for guidance.
Other Components
In addition to the Display, the Light Bars, and Sensors, you may also find the following associated equipment connected to the system harness and configured into the system:
Data Radio
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| Illustration 14 | g01178442 |
A data radio is used to receive data from a GPS reference station, or an ATS Instrument. The GPS/GNSS and the ATS Instrument require the data radio to be working correctly before they can be used in the system. The GPS data radio can also be used to send files and receive files and other types of data from the office.
Electric Mast
An electric mast is used to control the height of the ATS Machine Target above the cutting edge of the blade.
GPS/GNSS Base Station
Note: One of the following types of Base Station is required for the AccuGrade System to function correctly: GPS and GNSS. Currently, Caterpillar does not sell or service these Base Stations. A Trimble base station is recommended.
A Base Station consists of the following components:
- GPS Receiver or GNSS Receiver
- GPS Antenna or GNSS Antenna
- Radio
- Cables
- Power Supply
There may also be a tripod or mast for the GPS antenna and the radio, depending on the particular site. For construction sites where work can continue for a long time, use a semi-permanent location such as the roof of the site office. A reliable power supply is needed.
Make sure that the base GPS antenna is clear of obstructions, reflected GPS signals (multipath), and sources of electro-magnetic interference such as power lines.
The base station data radio must be elevated several meters off the ground in order to provide optimum coverage.
The GPS base station requires a starting location. For best results set up the base GPS receiver on a surveyed point. In order to establish this survey point, use a site calibration or a professional surveyor experienced with GPS equipment.
You must correctly set the GPS antenna type at your base station. If you do not, the GPS position is degraded.
Advanced Tracking System (ATS)
There are three main parts to an ATS:
- Machine Target
- ATS Instrument
- A Data Radio Link
Machine Target
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| Illustration 15 | g01181307 |
The Machine Target is mounted on one end of the blade.
The Machine Target has two sections:
LED Unit - acts as the target for the tracking system
Prism Unit - acts as a target for the electronic distance measuring (EDM) system
Note: The Machine Target must be mounted so that the prism unit is vertically above the LED unit. If the two units are not vertically in-line, the ATS may be able to locate and track the Machine Target, but will not be able to measure the distance to it.
ATS Instrument
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| Illustration 16 | g01239887 |
The ATS Instrument is a robotic theodolite capable of making high precision measurements of the azimuth, altitude and distance of the Machine Target.
Specially designed servo-motors work with the tracking software to allow the ATS Instrument to track the Machine Target moving at typical machine speeds. If the Machine Target is lost, then the ATS Instrument will try to predict how the Machine Target is moving, so that it can attempt to reacquire the Machine Target.
Note: In order to track the Machine Target reliably over a wide range of machine operating speeds, the ATS Instrument should be no closer than 15 m (50 ft) to the machine, nor farther than 300. m (985 ft) from the machine. The ATS Instrument must be mounted so that it is free from vibration due to wind or vehicle movements, and with a clear line of sight to the Machine Target over the full work area.
Data Radio Link
The data radio link consists of two data radios. One radio is located at the ATS Instrument. The other radio is located on the machine.
The link carries the position of the Machine Target, as it measured by the ATS Instrument, back to the AccuGrade System on the machine. The system combines the position of the Machine Target, relative to the ATS Instrument, with the known position of the ATS Instrument, in order to generate 3D target positions. The link also lets the AccuGrade System send commands back to the ATS Instrument.