I.Construction equipment control technology
Previously at construction sites, construction equipment operators visually confirmed stakes or other markers at the site that displayed the design values and controlled blade height by operating a lever.
Topcon entered the machine control market in 1994, when it purchased Advanced Grade Technology in the United States and acquired the hydraulic control and other technologies that are the fundamental technologies for operating construction equipment automatically.
Machine control systems to control relative height position
In addition to hydraulic control technology, height and position information must be captured electronically from external instruments in order to operate construction equipment automatically.
The first equipment for which this was practical was machinery for ground leveling work (to make ground flat). A rotating laser was employed as a height standard.
The next system to be commercialized was a three dimensional machine control system that used a total station with automatic guidance.
With both of these methods, the height and position of the device serving as a standard and the relative position of the construction equipment are measured.
Height information is sent from a rotating laser, and the laser sensor recognizes the amount of the change.
Based on the amount of the change, the hydraulic fluid flow rate is controlled electronically and the blade height is adjusted automatically.
Automatic blade control image
Machine control system (Robotic total station)
Based on highly accurate three-dimensional data from the total station equipped with automatic guidance, the blade is controlled automatically in line with the design values.
II. GNSS Technology
Measurement sent by electromagnetic waves from satellites
Topcon entered the precision GPS receiver market in 2000, when it purchased Javad Positioning Systems in the United States.
Topcon acquired Javad's precision GPS receivers as sensors to obtain machine control system position information.
With rotating lasers or a total station, operations could only be performed within a range of several hundred meters, the access range for light emitted from these devices. Using GPS to receive electromagnetic waves from satellites, however, made it possible to work at even larger job sites, as well as uniformly control several construction machines simultaneously, because the limitations on the access range were eliminated. In addition to GPS, Russia's GLONASS and Europe's Galileo have been added to the measurement satellites used, all of which are referred to generically as GNSS receivers.
By using GNSS receivers, it is now possible to measure absolute three-dimensional coordinates of construction equipment positions.
Machine control to control absolute position
3D machine control system (GNSS)
This is a system for performing semi-automated work; a control box installed in the cabin, which contains a record of the three-dimensional CAD data on the site, queries the absolute position of the construction equipment as measured by the GNSS receiver and controls the height of the construction equipment blade.
Currently the two companies with the largest shares of the global market for machine control systems using this GNSS receiver are Topcon and Trimble Inc. in the United States.