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| Illustration 1 | g01804133 |
AccuGrade System Overview for Compactors (1) GPS Base Station (2) Accelerometer (3) Alpha 30 Microcontroller (4) Drum Vibration On/Off Switch (5) Machine Data Radio (6) AccuGrade Display (7) Vibratory Amplitude Control Switch (8) MC 024 Microcontroller (9) Location Sensor (GPS Receiver) (10) Terminating Resistor (11) Drum Slope Sensor (12) RS232 Bus (13) 1Meg CAN Bus (14) 250K CAN Bus (15) Service Port | |
The main components of the AccuGrade System include the following items:
- GPS Base station (see note) (1)
- Vibratory Control System (2) (3) (4) (7) (8)
- Mapping and Data Acquisition System (5) (6) (9) (11)
Note: If necessary, low accuracy guidance can be provided using SBAS. SBAS does not require a base station or the infrastructure that is necessary to support high accuracy RTK Fixed measurements.
GPS Base Station
The GPS base station transmits the location of the base station, and the measurements that were made at that location, to one or more machine-based GPS systems (rovers) that are working near the base station. This permits the rover systems to generate corrections to the measurements. The rovers use this information in order to calculate highly accurate positions.
ReferenceFor additional information about the GPS base station and the components of the station, refer to Systems Operation, "General Information".
Vibratory Control System
Compactors that are configured with the AccuGrade System have additional components that are used to indicate the level of compaction. The components include the following items:
- Drum accelerometer
- Alpha 30 Microcontroller
- MC024 Microcontroller
- Remote switches for vibration control
Drum Accelerometer
The "drum accelerometer" measures drum vibrations. The vibrations are caused from the interaction of the drum with the ground. The accelerations are affected by ground stiffness. As compaction continues, the ground stiffness changes. The accelerometer indicates this change. The accelerometer signals are sent to the Alpha 30 Microcontroller.
Alpha 30 Microcontroller
The Alpha 30 Microcontroller contains the application that interfaces with the accelerometer that is mounted on the vibrating drum. Accelerometer signals are processed in order to produce values that indicate the level of compaction. These values are sent to the MC024 Microcontroller.
MC024 Microcontroller
The compaction control system incorporates an MC024 Microcontroller device for machine management. This device is connected to the Controller Area Network (CAN) bus on the machine. The MC024 Microcontroller contains the application that interfaces with the Alpha 30 Microcontroller and also with the remote switches that are located in the cab of the machine.
Remote Switches for Vibration Control
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| Illustration 2 | g01384042 |
Remote Control System Switches (4) Drum Vibration On/Off switch (7) Vibratory Amplitude Control | |
Two remote switches are used In order to operate the vibration control system. These switches are located in the cab to the right of the operator's seat.
Drum Vibration On/Off switch
The first switch is the "Drum Vibration On/Off" switch (4). This push-button switch is located on the top of the propel control lever. The switch turns the drum vibration on and off. "Dynamic mapping" will only occur when the drum is vibrating.
Note: In order to start the vibratory system, the throttle control must be placed in the HIGH position.
Vibratory Amplitude Control
The second switch is the "Vibratory Amplitude Control" switch (7). This 3-position rocker switch is located on a panel directly below the propel control lever. The switch is used to select one of three settings:
Low Amplitude - This setting is normally used for final compaction of soil. This is "Proofing Mode" during compaction mapping.
High Amplitude - This setting is normally used for initial compaction and for general high production work. This is production mode during compaction.
OFF - There is no vibration during compaction.
ReferenceFor additional information on the Vibratory Amplitude Control, refer to Operation and Maintenance, SEBU8504, "Vibration Controls".
Mapping and Productivity Data Acquisition System
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| Illustration 3 | g01518031 |
Machine Components (5) Data Radio (6) Operator Display (inside cab) (9) Location Sensor: GPS Receiver (11) Drum Slope Sensor | |
Data Radio
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| Illustration 4 | g01804213 |
A Data Radio (5) is used for receiving data from a GPS Base Station (1). Refer to Illustration 1. The information that is received from the base station is Compact Measurement Record (CMR) data. With the appropriate infrastructure, this radio may also send data to a centrally located office.
The CRXXX data radio is currently in production for use with the AccuGrade System. TCXXX radios may also be used. Both of these series of radios are available in the following frequency bands for compactors: 450MHz and 900MHz.
The radio is mounted with the radio antenna above the line of the roof on the cab. This location ensures maximum coverage for the radio. The radio is mounted to a plate specifically designed for both the CR series radio and TC series radio.
Note: For radio mounting information, refer to Special Instruction, REHS4671.
CR Series Radio Status Indicators
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| Illustration 5 | g01516144 |
(23) 2400 MHz Antenna (24) 900 MHz Antenna (25) LED (26) 8-pin Connector | |
The Series CR Radios are available in the following bands: 900 MHz and 2400 MHz. These products share a common housing and electrical interface in order to simplify the machine installation and integration. The Series CR Radios are a family of radios that are intended to replace the following Series TC Radios that are currently in use: TC900 and TC2400.
The 900 MHz band radios are used to receive GNSS data in Compact Measurement Record (CMR) format. This data is received from a reference receiver. The data is transmitted to one or more roving receivers for precise machine positioning. These radios can also communicate 2-way data between an office computer and the machine.
The 2400 MHz band radios are used to communicate location information for the ATS and commands from a base station to a machine for precise positioning.
These radios are offered in the following configurations:
Single Band Radio - 900 MHz or 2400 MHz
Dual Band Radios - 900/2400 MHz
The Series CR Radio has antenna connections on the top, an electrical connector on the bottom, and a LED on the front. Refer to Table 1 for the LED states.
| LED Status | Description |
|---|---|
| LED Off | No Power |
| LED On Solid | The Radio has power, but is not synced with the base station. |
| 1 Hz flashing LED | The Radio has power. The Radio is synchronized and receiving data. |
| Irregular flashing LED | The Radio has power. The Radio is synchronized, but the data is incomplete. |
The information that is contained in this document will guide the technician with the installation of the Series CR Radio.
TC Series Radio Status Indicators
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| Illustration 6 | g01381161 |
(16) Status LED (17) Connector | |
The bottom cap of the radio contains a status LED (16). This status LED indicates both data and power. The bottom cap also contains the connector (17). The connector is used for both power and for input/output. Refer to Testing and Adjusting, "Connector Contact Description" for pinout information for the radio.
The LED indicator will change color. The color depends on the situation. The meaning of each color is shown in Table 2.
| Radio Status LED Indicator Activity | |
|---|---|
| Color of LED Indicator | Status |
| Orange (solid) |
Power is available. No data is being received from the base station. |
| Orange and Green (both solid) |
Power is available and the radio is receiving information from a radio at the base station. This is the normal operating mode. |
| Orange and green (both flashing at 1 Hz together) |
The radio is in "flashloader" mode. Perform a power cycle of the radio. Contact the on-site manager if the mode returns at the power cycle. |
Operator Display
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| Illustration 7 | g01290067 |
The AccuGrade System uses the CD700 Display. This Display contains an on board computer that runs the AccuGrade software. This software features an operator interface that is easily understood. The interface provides compaction and guidance information to the operator.
The Display is located in the cab. The Display features a color Liquid Crystal Display (LCD) screen that can be read even in bright sunlight. The Display incorporates push buttons for operating the AccuGrade System. The Display can be tilted or the Display can be rotated for ease of operation.
There is a connector on the back of the Display that is used to connect the Display to the CAN bus. Refer to Testing and Adjusting, "Connector Contact Description" for pinout information for the Display.
The Display contains a slot for a removable "compact flash" data card. The data card is used for storing the data files for the machine. The data card is also used for transferring data to the Display and from the Display. The data includes design, compaction, and the GPS configuration.
Note: A wireless network may also be used in order to transfer the data. This is an advanced application that requires appropriate infrastructure, including properly configured radios and network connections.
Location Sensor
Location sensors are able to determine a position in three dimensional space. The AccuGrade System uses a GPS receiver (rover) location sensor. The sensor is used for measuring the position of the compactor's drum in three dimensional space. By using the appropriate base station or infrastructure, this measurement can provide very precise guidance to both edges of the drum. Guidance can be provided under a wide range of physical conditions and over very large sites.
Note: If necessary, low accuracy guidance can be provided using SBAS. SBAS does not require a base station or the infrastructure that is necessary to support high accuracy RTK Fixed measurements.
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| Illustration 8 | g01381167 |
(9) GPS Receiver (18) Status LED Indicators (19) Harness Connector | |
The system can use an MS980C GPS Receiver or else the system can use an MS990C GPS Receiver. Both of these receivers contain an integrated GPS antenna. The MS980C is a "GPS only" receiver. The MS990C can receive signals from GPS satellites and can also receiver other GNSS signals.
Note: In order for the MS990C to utilize the GLONASS signal, the base station must have a compatible "GLONASS-capable" receiver. SBAS is not readily available for GLONASS.
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| Illustration 9 | g01290033 |
GPS Receiver Access System
The GPS receiver is mounted on a steel mast. The mast is oriented directly above the center of the drum. The location is out of the immediate work area. This protected location ensures a clear view of the sky and optimal reception from the satellites.
A hydraulic system is mounted on the drum yoke. The mast can be raised into the operating position or lowered for maintenance with the hydraulic system. The system incorporates a locking mechanism for the mast. This mechanism ensures that the GPS receiver will always return to the same upright position. For information on raising and lowering the mast, refer to Operation and Maintenance, SEBU8504, "Startup".
GPS Receiver Status LEDs
The GPS receiver has three LED indicators (18) that are used to indicate the status of the receiver. The indicators are next to the Harness Connector (19). Refer to Illustration 8. When the mast is raised into the operating position, the LED indicators are visible to the operator. The behavior of the LED indicators aids in determining the status of the receiver.
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| Illustration 10 | g01363131 |
(20) Power LED Indicator (21) Data Link LED Indicator (22) Satellite LED Indicator | |
Table 3 shows the meaning that is associated with the activity of each of the LED indicators.
| GPS Receiver Status LED Indicator Activity | |||||
|---|---|---|---|---|---|
| LED Indicator | Off | Slow Flash | Flash | Fast Flash | On Solid |
| Power (20) | No Power | Power on | |||
| Data Link (21) | No CMRs received or too few satellites | CMR type 0 being processed | 10Hz CMR being processed (1) | ||
| Satellite (22) | No satellites being tracked | Tracking four or more satellites | Tracking three or less satellites | Monitor Mode (1) | |
| ( 1 ) | Applies to the second GPS receiver in a two receiver System |
| ( 1 ) | In addition to the satellite LED, the power LED will also be on solid. The data link LED will be flashing. |
When GPS is working correctly, the receiver's power LED will be on solid, the data link LED will flash at approximately one second intervals, and the satellite LED indicator will flash more slowly than the data link LED.
Harness Connector
The harness connector (19) for the GPS receiver is located to the right of the LED indicators. Refer to Illustration 8. When mounting the GPS receiver to the mast, ensure that the mating plug of the harness is securely locked into the connector.
Refer to Testing and Adjusting, "Connector Contact Description" for pinout information for the GPS receiver.
Drum Slope Sensor
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| Illustration 11 | g01290065 |
A slope sensor is used for measuring the cross slope of the drum. The slope sensor that is used by the AccuGrade system is the AS400C slope sensor. This sensor has a range of -45 degrees to +45 degrees with 0.1 degree of resolution. The sensor is mounted on the drum yoke at the base of the GPS receiver mast.
Refer to Testing and Adjusting, "Connector Contact Description" for pinout information for the Slope sensor.