News & Events
Trimble R12i TIP: A New Angle of Productivity
True North | Winter 2021
Introduction
For over 35 years Trimble has been a leader in GPS/GNSS surveying solutions. It is understood that while performing GNSS RTK/RTN surveys the rover receiver pole must be plumb during point occupation to eliminate systematic horizontal error. The new R12i eliminates this requirement by integrating TIP (Trimble Inertial Platform) technology into their newest receiver. This new GNSS/IMU based measurement method allows the user to perform rapid point collection and stakeout without a plumb rover receiver, increasing productivity and opening new applications for GNSS surveying.
Fig 1: Tilted Rover
Tilt compensation is old news, right?
When Cansel first learned about the newest Trimble R12i TIP technology, Canada had already been exposed to R10 and SurePoint™ technology.
Recently I had the opportunity to test the newest Trimble TIP technology. For starters, here are some high level differences between SurePoint™ and TIP:
- While SurePoint™ could measure a compensated point up to 15° away from plumb, the TIP can measure and stakeout a compensated point up to 30° from plumb.
- SurePoint™ takes a length of time for occupation of a compensated point, while the TIP has the ability to use Rapid point observation method, as well as point stake-out routine.
- SurePoint™ technology is susceptible to magnetic interference, while TIP is not as susceptible to magnetic interferences, increasing possible applications.
- TIP technology is a much more robust inertial measurement system that has standard errors associated with it and can therefore be considered more trustworthy than SurePoint™, which has no inertial capabilities and no standard error associated with the compensation measurement.
Real world testing: TIP
Trimble has made it relatively easy for us to validate this technology by providing us with reasonable standard errors for TIP on the R12i datasheet. Using the Network RTK positioning formula, combined with the TIP Technology formula, we attain a value for expected accuracy for any given point at any given tilt value up to 30°. When using tilt compensation, it adds +/- 0.005m + (0.0004m x n°) to the regular RTK/RTN equation. By separately calculating the expected RTK error using the distance to the base point as the variable, and the expected tilt error using the extracted tilt information as the variable, we can them combine these errors in squares, as they are both random and both measured in meters, to obtain a total expected error value for each occupation.
Real Time Kinematic Surveying | ||
---|---|---|
Single Baseline <30 km | ||
Horizontal | 8 mm + 1 ppm RMS | |
Vertical | 15 mm + 1 ppm RMS | |
Network RTK4 | ||
Horizontal | 8 mm + 0.5 ppm RMS | |
Vertical | 15 mm + 0.5 ppm RMS | |
RTK start-up time for specified precisions5 | 2 to 8 seconds | |
Trimble Inertial Platform (TIP) Technology | ||
TIP Compensated Surveying6 | ||
Horizontal | RTK + 5 mm + 0.4 mm/° tilt (up to 30°) RMS | |
Horizontal | RTX + 5 mm + 0.4 mm/° tilt (up to 30°) RMS | |
IMU Integrity Monitor | Bias monitoring | Temperature, age and shock |
Fig 2: Trimble R12i datasheet - Positioning performance |
Firstly, we established a known grid coordinate for our test point using traditional control surveying methods. This point was then occupied over 160 times at various orientations and tilt magnitudes. We then exported the data to a .csv including the tilt direction and amount. Using the .csv we organized the rows of data into order of ascending tilt amount and compared to ensure ∆2D from observed coordinate to the known coordinate is less than the expected amount of error (σexp.) based on the data sheet.
σexp. = expected error
RTKerr = RTK
error
TIPerr = TIP error
Results summary
Angle (Decimal Degrees) | ∆2D (Meters) | σexp. @ 99% (Meters) |
0.971 | 0.009 | 0.041 |
2.896 | 0.02 | 0.042 |
3.023 | 0.014 | 0.042 |
4.824 | 0.004 | 0.043 |
5.742 | 0.006 | 0.043 |
7.426 | 0.004 | 0.044 |
9.457 | 0.011 | 0.046 |
10.776 | 0.018 | 0.047 |
13.205 | 0.02 | 0.048 |
15.871 | 0.032 | 0.05 |
16.529 | 0.033 | 0.051 |
19.175 | 0.048 | 0.053 |
21.481 | 0.053 | 0.055 |
22.763 | 0.052 | 0.056 |
25.298 | 0.061 | 0.059 |
28.949 | 0.071 | 0.062 |
Fig 3: Results Summary |
A summary of the results shown above outlines the Angle of the receiver during the rapid point occupation, the 2D difference from observed to known, and the expected accuracy of the system for that individual occupation calculated based on the data sheet values. Comparing these real world test deltas to the expected values it is clear that very seldom were the actual deltas larger than the expected number, and if so, not by much. This leads me to believe the reported values in the data sheet can be trusted and were the result of many tests done by Trimble.
Cansel’s conclusion
While the R10 and R10-2 remain among the most trusted in the industry, R12i has set the new standard. The TIP technology provides unparalleled repeatability and accuracy. This, along with massive developments in signal tracking and processing (ProPoint), inspires the end user with confidence in data integrity and positional information extracted from the system.
Not only has TIP impressed us in terms of repeatability and accuracy, it has also brought productivity and applicable uses to an entirely new level. By integrating the high performance inertial system into Rapid point collection, as well as stake-out routines, time is saved on a per occupation basis, making the R12i the most productive Trimble integrated receiver to date.
Ryan Zinck
Geospatial Technical Support
Cansel