In addition to standard radiation sensors, a small frame can be attached to accommodate other instrument configurations, mirrors for daylighting applications or small parabolic dishes for thermal or fiber optic daylighting systems.
The MiniTrak is pole-mounted with a levelling bubble to facilitate precision installation. The unit will provide, without the use of the available calibration procedures, about +/- 0.25 degrees (4 mrad) of accuracy.
More accuracy can be obtained using the calibration procedure contained in the included PC Interface software. This interface is not needed for the tracking function but is useful for calibration and operational monitoring. Several tracking units can be networked to the same PC monitor using inexpensive RS-232 communications.
The MiniTrak instrumentation platform was designed at the request of engineers at Sandia National Laboratories to fulfill the need of more dependability and lower cost.
Equipment available previously were expensive ($10K), depended on external power, required external computer equipment for control and used stepper motors which drift due to skipping or missing steps. Other clock-motor versions require a daily visit to unwrap the wire from around the base of the rotating platform.
The MiniTrak system can mount ten instruments on the side rails. It uses photovoltaic panels (PV) to charge batteries for system power, uses the SolarTrak® embedded control system, doesn't drift and costs far less than previously-available products..
A new option just created for Sandia National Laboratories is the PSP Auto-Shade, used to calibrate solar insolation devices that measure ambient light and require periodic data baseline adjustments.
The unit is driven by the SolarTrak controller such that it changes state every 90 seconds (programmable by the user) and moves either 90 degrees or 180 degrees per cycle. This application is a good use of a stepper motor where little outside influence is involved that can make the motor skip a step.