Using an Autostar Telescope Positioner for Tracking Aircraft: Experimentation
The project goal is to develop a video tracking system to supplement precision tracking radars at low elevation angles. The initial experiment involved an Arduino, Nootropics Video Experimenter board, and an Amani GT plus some code written in Processing.
To be honest the Meade Autostar is better suited for tracking slow moving deep space objects instead of that which is considered more “local.” At least I can only assume it to be true as likewise I have yet to have success with the unit in the former arena. However the hardware is there: two-axis motor control with positional-encoder feedback, all via UART. The problem is, however, that the hardware interface is via a UART to a controller that is well documented to have buffering issues which ultimately leads to processor hangs and motor runaway.
More problematic is that there are only a few speed settings available via the uart; FAST! slooow, stop, reverse time-travel. The video below shows attempt at putting aircraft in track via a simple PI loop. The tracker attempt to lock, overshoots the target then hangs. Subsequent attempts to bring the target back into track succeed temporarily and ultimately results in a runaway gimbal.
The next step is to open the Autostar, tap into the DC motor wiring, and provide a nice dynamic range of control speeds via the Amani GT and an H-Bridge PMOD. The UART connection will be maintained for positional encoder data.
It should be noted the control-loop bandwidth will then be limited by the Arduino/Nootripics assembly. While the video experimenter is a fantastic proof-of-concept tool, the design will eventually be migrated to an FPGA-based system where data can be collected and processed in real-time and passed to the host machine via ethernet. Moreover the control-loop itself will reside in the electronics package; the host PC will only provide a user control interface and data display.
Open Autostar picture courtesy of RobRoy.
Posted: April 17th, 2012 under Arduino Application, Demonstrations.
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