The S6 total station series by Trimble.

With the launch of the new S6 total station series by Trimble last month, I visited the Westminster, Colo., facility. The S6 is a new servo-driven total station that can be upgraded to target tracking (Autolock) and robotic functionality. This series is built on a completely new, lighter and more compact hardware platform from Trimble's earlier versions.

According to Roger Höglund, manager for Trimble's portfolio of servo-driven total stations, "We developed a combination of new technology initiatives-a response to issues from user requests for higher productivity and the desire to raise the level of integration of subsystems on our total stations. To meet these needs most effectively, and to position ourselves for further developments in the future, Trimble decided to move from the platform currently used for the 5600 [series] and prior total station models to create a new platform for the times. The result is a platform that maximizes the benefits from the technological advances that we've brought together in this instrument."

Leading the developments are a trio of Trimble trademarked features: MagDrive, SurePoint and MultiTrack. For the casual observer, perhaps MagDrive is the most readily apparent. Gone is the trademark whine of the servo motors as they position the instrument's telescope. Trimble has developed a drive system that capitalizes on the developments of magnetic levitation technology implemented in trains and other devices. In effect, the drive motor for each axis is roughly the shape and size of the housing for the angle encoder circle. The 5600 used a circle reading system that used the measurement of magnetic fields instead of optoelectronics. In the S6, Trimble has introduced a pair of diametrically opposed optoelectronic sensors on each axis to read the circles. But the drive system, as with all motors, relies on the forces generated by magnets. Trimble's system, which does not use any motion locks, is apparent when power is turned off: the instrument rotates with no resistance. All the resistance felt by the user during surveying operation is provided by the magnetic fields. In addition to being silent, the MagDrive allows the in-strument to reverse face (that is, to rotate about its horizontal and vertical axes so that it is pointing at the target in Face 2) in just over three seconds; Trimble claims its rotational speed to be 115° per second.

Because of the features of MagDrive, SurePoint, the second of these high-tech features becomes feasible. SurePoint detects accidental nudges and vibrations from the operator and environment, and continues to keep the telescope pointed at the target. Yet, if the user wants to point at a different target, the instrument may be rotated by hand or with the horizontal and vertical motion knobs. In addition, this feature is coupled to the compensator so small changes in the vertical axis of the instrument due to such factors as settling and expansion or contraction of the tripod legs result in the telescope being repointed at the target-automatically. Because of the way SurePoint is implemented, it is actually possible to now track a vertical line with the telescope and keep the horizontal angle constant; the MagDrives change the horizontal angle as the vertical angle changes to compensate for errors due to leveling and lack of horizontality of the horizontal axis.

With MultiTrack, Trimble marks another significant departure from its previous instruments: when in prism tracking or robotic modes, a standard prism may be used. Until now, Trimble instruments have required an "active" prism to implement these features. The "active" part was an infrared emitter integrated into the prism so the tracking technology could seek it and point precisely to it. However, with the introduction of tracking using standard prisms, Trimble has added automatic ID of targets through an accessory device that attaches to the prism pole just below the prism. This, in effect, provides a different and optional active prism mode, and supports the use of multiple instruments onsite without fear of confusion. This device can be programmed to emit one of eight different codes through its infrared transmitter. When the controller software of the S6 has been set up to observe measurements to targets with the designated ID, the instrument will not track the "false" targets. The tracker system is now integrated into the telescope, and with the EDM and laser pointer, co-axial with the telescope optics used for visually sighting targets.

While these features have significant operational benefits, the S6 also includes a second (smaller) display on the Face 2 side of the instrument. It can be used even if the main display has been removed (for robotic or GPS work) to: set up the instrument, including leveling; initiate measurements; perform various calibration routines; and visually observe the result of measurements in a variety of modes. Another departure from the earlier series of total stations is that the optical plummet is now built into the alidade of the instrument. This eliminates the need to use an optical plummet tribrach, and has the added benefit of the ability to quickly check that the plummet is in adjustment with every setup. Other features include a much longer battery life of six hours in robotic mode with the new, intelligent Li-ion batteries, which are automatically given a deep discharge/ recharge cycle if the five place charger detects that the batteries have been subjected to shallow cycles. This new charger can also charge GPS system batteries.

The offset handle of the S6 allows vertical observations to be taken. Not only are the displays and reticle illuminated, the keyboard has a backlight as well, so the instrument can be used in adverse lighting conditions without exterior lighting. To further facilitate operation, in addition to the variable speed horizontal and vertical control knobs on the right standard, focusing is done using a knob on the right standard also, which electrically changes the focusing elements in the telescope. When coupled with the multifunction trigger key, located next to the motion control knobs, most operations can be done without removing one's hands from the right standard, which functions as the control "instrument" panel or one's eye from the telescope.

Orders for the S6 have already been placed. One of the first orders came from Fred Mueller, a principal of Psomas (Los Angeles, Calif.) who is responsible for the firm's field operations and construction surveying. When asked about his decision, Mueller said, "Psomas has a long history of association with Trimble. I've visited the total station factory in Sweden, and that experience has given me confidence that this new instrument will improve our operational factors even more. Most impressive for me are: total absence of cables in the field, either with the total station in robotic mode or when using the controller with RTK GPS; extra long life of the batteries; and threefold improvement in the speed of the instrument to turn to a point."

Further improvements in the operation of a total station are facilitated in the S6 with the creation of Survey Controller version 11 software, which resides in the new Trimble controller unit (TCU). The TCU seamlessly attaches to the instrument for servo and autotracking modes, moves to a robotic cradle for robotic mode, and integrates using Bluetooth technology with RTK GPS. One of the features that Survey Controller enables is voice prompts that are integrated with total station operation. The TCU also supports the ability to access application programs using the Geodimeter program command numbers.

The EDM of this total station is the reflectorless 300+ technology currently offered in the 5600 series. It is anticipated that once production is in full swing of the S6 Trimble will also offer standard Direct Reflex (DR) EDMs. Coupling this EDM with MagDrive will enable the instrument to function as a slow scanner, measuring 30 points per minute.