For Owners
Description of the ECS
The Toomey ECS – Elevation Compensation System - is our unique way of compensating for the changes in elevation experienced throughout the day when using GPS for height control for earthmoving or surveying.
The system determines elevation “shifts” or “drift” by using the real time elevation from a stationary GPS Rover and then using that information to physically adjust the GPS Base station height with the use of the included linear actuator. The object of the exercise is to maintain a constant elevation at the stationary Rover.
There are two factors which, when combined, allow the ECS concept to work.
Firstly, the Base Station has a direct effect on the Rover similar to how a Laser Transmitter relates to a Laser Receiver i.e. if you change the height of the Base Station; the Rover experiences a similar elevation change.
Secondly, most Rover receivers experience a similar “drift” amount at roughly the same time. There are differences in “drift” figures at different base line distances though practical reality suggests that these differences are marginal and acceptable in most applications.
NOTE: It is worth mentioning that the “drift” values start from nothing within a few meters of the Base Station and grow out to about 150 meters from the Base Station from where it appears that only marginal variations occur. It has been seen that on hotter days (above 35C, this distance could be a bit further). Therefore, our advice is to have the Base Station no closer than 150 meters from the working area and to put the Rover at the midpoint of the working area.
Components
The system comprises three major components;
ECM or Elevation Compensation Module; this is the main Control Box.
Rover Module or RM.
Note: Both the ECM and RM are fitted with 900 MHz Spread Spectrum radios.
Actuator.
The cables and accessories include
ECM Power Cable.
RM Power/Serial Cable.
ECM Radio Antenna and co-axial cable.
RM Radio Antenna and co-axial cable.
Direct Connect Serial Cable (ECM to RM).
OPTIONAL - John Deere Serial/Data Cable (if supplied to suit a John Deere system)
Long Tripod brackets (2 of).
RM Tripod Mount bracket.
The system comprises two major components and cables. A GPS Rover Receiver is also required and this can be supplied as an option. This can also be sourced from your local GPS retailer or you may have a spare unit not being used that can be added to this system. The first component is the ECM or Elevation Compensation Module, this is the Control Box. The other component is an Actuator orElectronic Mast.
System 2 Requirements
A 12 volt power source is required for the Elevation Control Module and the Bluetooth Module.
NOTE: The use of solar panels to charge a battery while running any GPS Receiver is discouraged as voltage changes can affect the GPS receiver and result in fluctuating elevation figures. It is advised to have two batteries if running solar panels – one being charged and one running the GPS.
A GPS Rover Receiver is also required to provide a stationary elevation solution. This can also be sourced from your local GPS retailer or you may have a spare unit not being used that can be added to this system. The rover receiver must be able to acquire an RTK “fix” from the Base Station. The Elevation Control Module only works with an RTK NMEA output. The stationary Rover Receiver must be configured to output a NMEA GGA String @ 1Hz and 38.4K Baud rate. Please consult your GPS Rover supplier for support.
Considerations
The vertical accuracy of the GPS solution varies between locations and times. It is also affected by atmospheric conditions.
The use of the ECS assumes that local conditions are stable though no guarantees are implied.
The “dead band” or “neutral zone” of the ECS is fixed (+/- 3mm or 1/100’) and no adjustments can be made.
The ECM is factory calibrated and only basic speed adjustment can be made to the unit by the operator.
The repeatability of this system currently relies on both the Base tripod and Rover tripod being stationary throughout the course of the project. If at any time either of the tripods are moved and reestablished, a different height may eventuate. It is wise to have a firm pad graded to return the grader to in order to reestablish the correct blade height.
Set up Instructions
ECM Setup at the Base Station
Remove the Actuator from the carry case and mount it to the top of the base station tripod with one of the supplied brackets between the tripod and the actuator base as shown in Figure below.
Note: A Trimble AG25 antenna and Radio antenna are shown for reference only.
Mount the Base Receiver or Antenna (depending on the type and style of GPS hardware being used) to the thread at the top of the Actuator. For Trimble Ag GPS receivers, the Trimble radio mounting bracket can be placed on top of the Actuator under the base antenna.
Mount the Elevation Control Module to the bracket with the co-axial bulkhead connector facing up and going through the cutout in the bracket. Fit the 900 MHz Radio antenna connector onto the bulkhead connector and this holds the ECM in place.
Connect the cable with the 3 pin Mil Spec Connector to the panel mount on the bottom of the Elevation Control Module as shown in Figure below
Connect the cable with the 6 pin Mil Spec Connector to the panel mount on the bottom of the Elevation Control Module as shown in Figure below
At this point, the Actuator will cycle, going down first, have a rest for a few seconds and then move up and stop in the middle of the shaft travel.
The Elevation Control Module has initialized and is ready to start operation.
900 MHz Radio Modem connection to Rover
To communicate between the Elevation Control Module and GPS Rover wirelessly, mount the Rover receiver to the tripod at a suitable distance from the Base Station (from 400 - 2,000 meters) with the supplied bracket between the Rover receiver/antenna and the tripod. Fit the Rover Module to the small angular bracket using the antenna co-axial connector as the retaining nut.
Connect the Rover Module Power Cable with the 6 soc Mil Spec Connector to the bottom of the Rover Module housing. Connect the serial cable to the Rover receiver with the appropriate serial connector (there are two options to choose from).
Connect the alligator clips to a battery. The modem will start transmitting the NMEA data to the Elevation Control Module from the GPS Rover (refer to your GPS Manufacturer’s User Manual for the instruction on outputting the NMEA)
NOTE: The ECM can be mounted in a similar manner.
Hard wired connection to the Rover
To communicate between the Elevation Control Module and GPS rover with a physical cable as opposed to the RM option listed above, follow the instructions below.
Connect the serial data cable from the rover receiver to the serial port on the Elevation Control Module. Connect the other end to the GPS Rover; there are two plugs, one for Trimble Ag products and a generic RS-232 plug for the other products on the market.
Starting the Compensation
After the Elevation Control Module is powered up and the actuator has cycled, the system is ready to accept the NMEA data from the Rover. During this power up cycle, the Firmware version is displayed. When the Actuator cycle is complete, the top line of the screen will display the word WAIT.
Once the Rover GPS has initialized and configured correctly, it should start sending a NEMA GGA string to the Elevation Control Module. If this is successful, the NMEA RTK OK LED on the Elevation Control Module will illuminate and start pulsing when using either data transfer method. The top line in the display will then show the accuracy status (Autonomous, Float) until an RTK NMEA signal is received. Once an RTK NMEA signal is received a momentary FIX will display, followed by the height coming from the Rover (OBS or Observed Height).
NOW FOR THE REALLY DIFFICULT PART!
Press the START button.
The Actuator is now under the control of the Elevation Control Module. The OBS Height value now drops to the bottom line and becomes the SET Height while the top line still shows the Observed Height coming from the Rover. The Elevation Control Module will try and maintain the top line height by adjusting the height of the actuator so the Rover is producing the same height as the SET value.
Depending on the GPS solution, the speed of correction speed may need to be adjusted to achieve the most suitable outcome. There are only three speed options. The slower the correction results in a smoother the result. If the GPS solution is changing rapidly, an increase in correction speed might be required.
Troubleshooting
No NMEA RTK OK LED pulsing. Visually check the rover has an RTK fix. Run the supplied test cable from the rover to the Elevation Control Module. If the LED is pulsing there is a Bluetooth Modem issue – consult the manufacturer or representative.
No movement in the Actuator. Check for NMEA RTK OK LED. No LED means no actuator movement. Refer to step 1.
No power LED. Check battery voltage (yes, it does happen!) Erratic and excessive movement of the actuator. Please read the Disclaimer below.
NOTE: It is strongly advised to use a similar level of GPS technology and firmware for both stationary GPS Rover and the mobile Levelling Receiver. Receivers with different GPS shipsets and antennas can produce a different elevation solution.
DISCLAIMER
The ECS is not a GPS System. It merely uses the data supplied by the GPS rover receiver to maintain a stable working platform for mobile rovers. No level of accuracy or repeatability is implied. There are times when the GPS may be unusable due to a number of factors which include both atmospheric influences and the poor satellite positioning in the sky.
Note:
The ECM has a 9DB pin (male) connector. Serial data input into this connector is as follows;
Pin 2- RS232 Data In, Pin 5 – RS232 Data Ground
2. Bluetooth Connectivity. A cable and adapter is supplied with the DB9 Serial connector to fit a number of GPS receivers. Connect the serial connector into the GPS receiver harness.
Next, power up the Rover GPS.
Once the Rover GPS has initialized, it should start sending a NEMA GGA string to the ECM. If this is successful, the NMEA RTK OK LED will illuminate and start pulsing when using either data transfer method.
Press the START button and the Actuator is now under the control of the ECM.
Depending on the GPS solution, the speed of correction speed may be adjusted to achieve the most suitable outcome. There are only three speed options. The slower the correction, the smoother the result. If the GPS solution is changing rapidly, an increase in correction speed might be needed. This is your only adjustment.
USER MANUAL (5 MB)
TROUBLESHOOTING
+ No NMEA RTK OK LED pulsing
Visually check the rover has an RTK fix. Run the supplied test cable from the rover to the ECM. If the led is pulsing there is a Bluetooth Modem issue – consult the manufacturer or your representative.
+ No movement in the Actuator
Check for NMEA RTK OK LED. No LED means no actuator movement. Refer to step 1.
+No power LED
Check battery voltage and power supply. Check all leads are connected correctly. (yes, it does happen!)
+Erratic and excessive movement of the actuator
Please refer to the Disclaimer below. Turn all power off and power up again to reset system.
DISCLAIMER
The ECS is not a GPS System. It merely uses the data supplied by the GPS rover receiver to maintain a stable working platform for mobile rovers. No level of accuracy or repeatability is implied. There are times when the GPS may be unusable due to a number of factors which include both atmospheric influences and the poor satellite positioning in the sky.
