A Concise Guide for Sokkia SET5F Total Station

CIVL 102 Fall 2006 Traversing Lab Guide Objective: obtain E, N of stations A-x & C-x (same as those used in your leveling lab, e.g. A-1 & B-2) to the nearest mm by closed-loop traverse on triangle B-x  C-x  A-x using 3-tripod traversing. unknown point (A-x) Known point (AA) Do NOT enter this grass area!!! WIP Known point (B-x) ** Station AA will be set up by the TAs and forms the baseline with your known station B-x (coordinates of AA and all B-x points will be given in Nov. 8 lecture). unknown point (C-x) Fig. 1 Location of traverse stations and reference point AA Instructions: 1. Proceed anticlockwise around the loop, measuring each internal angle (clockwise) from back station to forward station, e.g. from A to C while at B. Use the 3-tripod system. Measure all angles in both the FL (face-left) and FR (face-right) modes. Don’t forget to measure the angle AA-Bx-Cx to orient the traverse. Take the average zenith angle, ZAavg = [FL + (360 – FR)]/2 after sighting the same target in FL and FR. 2. Each slope distance must be measured in both “forward” and “backward” directions (e.g. from A to B, and also from B to A). In each direction, (slope distance)sin(ZAavg) = plan distance (obtaining Lfor or Lback). For your least squares adjustment, the observed plan distances L are the averaged values, i.e L = (Lfor + Lback)/2. 3. When exchanging target and theodolite, hold the instrument firmly in your hands and walk carefully. If the instrument is carried with tripod, always keep the whole assembly vertical and hold it by the tripod legs; DO NOT carry it over the shoulder. DO NOT hold the theodolite and let the tripod’s weight hang on it. 4. After the lab, when storing the theodolite, please loosen all clamp screws to avoid “accidental forcing”. Refer to the pictures on the box when storing the prism set. Leveling and Centering a Theodolite or Total Station We measure angles with theodolites (this may be embedded within a total station). A theodolite consists of the tribrach and the theodolite body; these can be separated if the tribrach fixing lever is released. You must keep this lever locked at all times except when exchanging theodolite-target, or the theodolite may fall off. The tribrach’s base is fixed to the tripod, while its top is fixed to the theodolite body. The three levelling screws on the tribrach can be adjusted to level things above the tribrach (e.g. the theodolite). A theodolite must be centered and levelled to produce accurate readings. It has an optical plummet for centering over a survey point, a circular bubble level for rough levelling, and a plate level for precise levelling. Setting Up the Tripod: (this important step saves much time in subsequent adjustments!!) Extend tripod’s legs to a proper length (~ shoulder height), and set it approximately over the marked survey point. The tripod head should be roughly horizontal, and each leg should be about 70 from the ground. If the legs are not well spread apart, the whole assembly may fall easily! Lift the tripod and redo the above if necessary. Avoid having a tripod leg coming at the observer, which may cause inconvenience. Remove the theodolite from its box, attach it to the tripod, and fasten the large bolt underneath the tripod base. Make sure the tribrach base and the tripod head (both triangular) are parallel and share the same centroid to permit maximum translation in any direction later on. Remove the lens cap, put it back into the carrying case, and close the box. Setting Up the Theodolite: (“RC-RL-PL-PC“) (1) Rough Centering: Secure the front tripod leg. Hold and move the two other legs while looking through the optical plummet to roughly center the theodolite. Use the right foot placed near the mark as a guide; see Fig. 1. Secure the tripod legs when done. Center mark of optical plummet to roughly coincide ground mark right foot Fig. 1 (2) Rough Levelling (use the circular bubble as the guide): Adjust the length of one tripod leg at a time while keeping the other two still, to level the circular bubble without causing much disturbance to the previously accomplished centering (check the optical plummet to see this is true). (3) Precise Levelling (use the plate bubble as the guide): Rotate theodolite to have plate bubble parallel to two footscrews (A and B), then adjust A and B to center the bubble. Left thumb rule applies: bubble travels in direction of left thumb. Now rotate theodolite body by 90, and center the bubble with the third footscrew (C) only. Now check the optical plummet: adjustment of the footscrews affected the centering. (4) Precise Centering Loosen the tripod screw, and slowly translate (do not rotate) the theodolite around until it is exactly centered over the survey point, then tighten the screw. (5) Repeat (3) and (4) until levelling and centering are both accomplished precisely. Vertical circle 90 Horizontal circle Zenith 270 180 0 Theodolite in Face Left: Zenith angles ~ 90 when telescope is horizontal Zenith 360 Face right = vertical circle to the right of telescope 270 90 180 Theodolite in Face Right: Zenith angles ~ 270 when telescope is horizontal *** To avoid damage, pleas do not turn any footscrew excessively (over 3 complete revolutions), and do not rotate anything by force *** A Concise Guide for Sokkia SET5F Total Station Setting up the instrument:  Center and level the instrument as usual. Refer to the theodolite setting-up procedures.  Never put the total station directly on the ground (to avoid scratching bottom of tribrach). Power On/OFF:  To turn power on: press the yellow Esc key  To turn power off: press and hold down Esc and press OFF  When powered on, you will see three items displayed on the right, under “ppm/P.C.”: o top: ppm correction (e.g. 9) o middle: Prism Constant (-30 is correct for Sokkia prism; don’t change it) o bottom: Battery fullness (3 = full; 2 = 50-90%; 1 = 10-50%; 0 = 0-10%)  Ignore the backup battery warnings (used for internal memory which you don’t need) Indexing the V & H circles (i.e. initializing the V & H angle readings) After turning instrument on, loosen the vertical and horizontal motion clamps. Rotate upper part of total station in both H and V planes until both H and V angle readings are displayed. Making angle and distance measurements:  Make sure the total station is in THEO mode. If needed, you can press Esc to return to basic menu and then press THEO to go to theodolite mode. The “Zenith Angle” and “Horizontal Angle Right” (i.e. angle value increases when turning clockwise) are displayed.  Adjust focus knobs for the reticle and then for the target; re-focus to eliminate parallax if any.  If you want to zero-set the horizontal angle reading, use the arrow key to go to page 2 and press “0 SET” once, while in face left. The horizontal angle becomes zero.  Press Sdist to measure slope distance. The total station will measure the slope distance 3 times (S1-S2-S3), then display average value (S-A), e.g. 2.2328 m. Press STOP if needed. Some other functions of this total station (not used in this lab)  S-O: setting out mode  EDM: EDM mode  CONF: settings configuration mode  RESEC: resection mode  REM: Remote elevation mode (trigonometrical leveling)  REC: record instrument station data and measured data (RCL to review)  EXIT: to exit from each mode Optional: inputting weather parameters (which govern the correct ppm correction):  Press THEO to go to theodolite mode. The “Zenith Angle” and “Horizontal Angle Right” (i.e. angle value increases when turning clockwise) are displayed.  Bottom of panel shows the options Sdist, REC, MEM, P2.  Use P2 to go to page 2 of the menu, and press ppm, 2 (for temperature & pressure), then use  keys to change the sign/number, or  to shift to the next character. Press Enter when done. When done with all input, Enter to go back to the theodolite mode.  Note: if you cannot find ppm under THEO menu, try the EDM menu A Concise Guide for Topcon GTS-211D Total Station Setting up the instrument:  Center and level the instrument as usual. Refer to the theodolite setting-up procedures.  Never put the total station directly on the ground (to avoid scratching bottom of tribrach). Power On/OFF:  To turn power on or off: press the green power key at lower right-hand corner.  When powered on, you will see the battery indicator: “” means full; “=” means OK; “– “ means low. Indexing the V circle (i.e. initializing the V angle readings)  After turning on, loosen vertical and horizontal motion clamps. Rotate telescope in a vertical plane until zenith angle readings are displayed.  The V (i.e. zenith angle) and HR (horizontal angles right, i.e. angle value will increase as it goes to the right) should be displayed. Making angle and distance measurements:  Adjust focus knobs for the reticle and then for the target; re-focus to eliminate parallax if any.  Use 0SET to set the horizontal angle reading to zero (while in face left) if desired.  Press the “triangle” key (with 3 lines: vertical, horizontal and inclined) to start distance measurements. The total station may take repeated measurements of the slope distance (SD), then display the calculated horizontal distance (HD*). This will consume a lot of battery if not stopped.  Press MEAS once to make a single distance measurement. A common practice is to measure 3 times and use the mean for accurate work.  The display may not show what you want, e.g. it may show HR (Horizontal angle), HD (Horizontal Distance) and VD (Vertical Distance), while you want V (Zenith angle), HR, and SD (slope distance). You can press the triangle key to switch to the desired display mode to show the latter three instead. The “triangle” key ** Assume angle = 5” and distance = 5mm when performing adjustment calculations ** Report Format: All reports must be typed, printed on A4 size paper, except the map which must be printed on A3 paper. All pages must be stapled together. Include: 1. Title page: course title (CIVL 102), lab name (Three-tripod Traversing), group number, member names with student ID numbers, lab date and report submission date. 2. Calculations and results: use the Excel sheets posted on http://teaching.ust.hk/~civl102/menu/traversereport-form-2006.xls (turn in hardcopies, not files) 3. A3-map: Include a plot of your adjusted traverse, plotted at 1:500 scale on A3 paper. Dimension all angles (in D/M/S format) and distances (to nearest 0.001 m). Include grid lines at integer multiples of 50 m. It should look similar to the following: 800600mN AA A1 800550mN B5 800500mN C3 810200mE 810250mE 810300mE 810350mE LEGEND: Traverse station 4. Discussion of the error: quantitative and qualitative aspects, including -- where do you think the error came from? How can you avoid or reduce it next time? Any lessons learned from this lab? Also report any irregularities here (e.g. faulty equipment/ damage to equipment/ etc.). Limit this to 1 page. 5. All original booking forms from the lab must be attached at the end of the report, with the collected field data presented neatly. Due date: Dec. 8, 2006 (all groups). Please submit to the CIVL 102 collection box outside room 2126