WHAT IS CHECK AND ADJUST AND WHY/HOW OFTEN IT HAS TO BE DONE?
Leica Total and Multi Stations are manufactured, assembled and adjusted to the best possible quality. However large temperature changes, shock or stress can cause deviations inside the instrument. The Check and adjustfunctionality offers a great opportunity for the user to not have to think about these deviations whilst measuring. Corrections for the deviations can easily and quickly be determined within the Check and adjust procedure and after that subsequently applied to all measurements.
As mentioned above the Check and adjust procedure should always be done after the instrument had sustained large temperature changes, shock or stress. This can be due to working under extreme weather conditions or after a transport of the TS/MS or even if the instrument has not been used over a period of time.
The Check and adjust procedure for SmartWorx Viva and Leica Captivate Total Stations is described in detail in the instrument user manuals. In the following sections on this page we recommend certain amendments/adaptions to the standard procedure outlined therein to account for the specific accuracy requirements and environment the instruments are operating in.
Our general recommendation is to install a permanent Check & adjust facility in a stable area close (i.e. within a couple of kilometres) to the construction site. All instruments used on that site should run through the Check & adjust procedure before they are used on that construction site.
WHAT ARE THE OPTIMUM MEASUREMENT CONDITIONS?
Check & adjust measurements should be carried out with all instruments under similar environmental conditions to ensure consistency among instruments.
Strong heat shimmer and air turbulences as seen on the image below should be avoided. The best time for a Check and adjust procedure would be early in the morning with covered sky. If possible it should be avoided to carry out the Check and adjust procedure under sunny conditions. Ideally the measurements are always carried out by the same person.
INSTRUMENT SETUP AND ACCLIMATISING
The instrument should be set up on a stable pillar and must be protected from direct sunlight. Before starting the onboard Check & adjust procedure the instrument should become acclimatised for 2 minutes per °C temperature difference, but at least for 15 minutes.
During the acclimatisation time the instrument should be turned on to allow the instrument’s electronics to warm up to operating temperature. In case the instrument comes from the office where the temperature is 22° Celsius and the temperature on the site is 0° Celsius, the instrument should be given 44 minutes to acclimatise.
WHICH PRISM SHOULD BE USED FOR CHECK AND ADJUST?
The Check & adjust procedure should be carried out using a standard Leica GPR121 circular prism mounted in a metal holder with target plate. The prism must be clean and the correct prism type must also be selected in the onboard software during the Check & adjust routine.
The prism should be in the shade and it must be made sure that no light sources or reflecting parts are in the vicinity of the prism within the field of view of the telescope. In order to ensure consistency of the ATR calibration between instruments, the manual aiming to the target must always be done in the same way (i.e. always either using the target plate or always directly aiming to the prism center).
WHAT IS THE RECOMMENDED DISTANCE TO THE PRISM?
We recommend a distance of approximately 80-100m. This should provide the best combination of:
- Providing high ATR accuracy
- Representing typical ranges used during regular operation
- The ability to do precise manual aiming to the prism
during the Check & adjust routine.
HOW OFTEN SHOULD THE CHECK AND ADJUST ROUTINE BE REPEATED?
We recommend to measure at least three sets of two face measurements during the Check & adjust routine to increase measurement redundancy and the robustness of the calculation. After the first two face measurement additional measurements can be added.
The results of the Check & adjust measurements should only be accepted if all σ values in the Adjustment Accuracy panel after three sets are not greater than 0.0003 gon. Otherwise the results should be rejected and the whole procedure should be repeated. This is to prevent that outlier measurements caused by e.g. bad manual aiming of the operator are included into the calculation.